A lot has been made here and on other MK boards about the dangers of large roster overhauls in fighting games. I thought I'd examine the notion more closely and take a look at the other two biggest fighting game franchises (in my opinion) and how they've handled large roster overhauls.

STREET FIGHTER
The overhaul I've seen MKX compared to most is Street Fighter 2- Street Fighter 3. Because of the method of release Capcom uses for Street Fighter, I'll use the definite roster of each subseries. The roster in Super Street Fighter 2 was:

RETURNING
Ken
Ryu
Sagat (CPU)

NEW
Akuma
Balrog (CPU)
Blanka
Cammy
Chun Li
DJ
Dhalsim
Honda
Fei Long
Guile
Bison (CPU)
T Hawk
Vega (CPU)
Zangief

The most notable thing about that roster is that all of the new characters are essentially Street Fighter staples. The reason for this is that the original street fighter was pretty disconnected from a true fighting game, as in you could only play Ryu or Ken if you were Player 2. So the roster introduced in the Street Fighter 2 series is essentially the heart of Street Fighter: pretty much the UMK3 roster equivalent.


The major overhaul came in SF3. When SF3 was initially released, the response was ambivalent, mainly because of the almost total change in the roster: very few characters had any relation to others in SF2 and almost all movesets in the game were totally new. Even though the ratio of new to old characters was higher in SF2, SF2 had no real legacy to build on, while SF3 built on SF3. Later iterations of SF3 did incorporate older characters, like Akuma, Chun Li and Dhalsim, but the initial SF3 had only Ken and Ryu returning.

These days, SF3 and 3rd Strike in particular is revered as one of the best fighting games and one of the best arcade games of all time, and recently Daigo called it the greatest fighting game of all time. High praise.

The roster for 3rd Strike was:

RETURNING:
Akuma
Chun Li
Dhalsim
Ken
Ryu

NEW:
Alex
Dudley
Elena
Gill
Hugo
Ibuki
Makoto
Necro
Oro
Q
Remy
Sean
Twelve
Urien
Yun and Yang

Not only has the game itself gained more fans as it aged, but several of the new characters, initially maligned have gained increased prominence among SF fans: Dudley, Hugo, Elena and Ibuki in particular.

So what can we learn then? Initially, SF3 was met with a lukewarm reception as it changed not only several gameplay mechanics but almost the entire roster was new. However, it gained traction and appreciation and is now remembered as a classic fighting game.

TEKKEN
This is the other major fighting game series in my opinion. (I don't want to get into a debate over others but basically I'm running with SF, MK and Tekken being the big three with DOA, KI, KOF and VF being the rung below).

There have been more major roster overhauls in Tekken than either MK or SF: only one character has been playable in all Tekkens: King (and even then, the man beneath the mask changed, like Sub Zero).

The roster from Tekken 1 to Tekken 2 was fairly similar, albeit with Tekken 2 naturally adding some characters: no character from Tekken 1 failed to make the Tekken 2 roster, while Roger/Alex, Lei, Jun, Baek and Bruce made their debuts. So the roster was:

TEKKEN 2

RETURNING:
Anna
Armour King
Ganryu
Kuma
Kunimitsu
Law
Lee
Prototype Jack
Wang
Heihachi
Devil
Jack 1/2
Kazuya
King
Michelle
Nina
Paul
Yoshimitsu

NEW:
Alex/Roger
Angel
Baek
Bruce
Jun
Lei

This is very much a classic fighting game roster evolution: add a few characters, keep all the classics and it led to Tekken 2 becoming one of the greatest fighting games of all time and one of the best selling fighting games in history.

To do what Namco did next took serious spine: they totally overhauled their roster and characters, introducing new movesets and moving away from their classic look into a more modern look, complete with heavy metal soundtracks.

Tekken 3 became an instant classic for several reasons: gorgeous graphics, amazing designs, an excellent fighting system that was at once accessible and competition-worthy. It is the second best selling fighting game of all time, one of the greatest games ever made and in my opinion, the greatest fighting game ever.

This contrasts with SF3: SF3 gained a high degree of adulation but only after several years of lukewarm reception, whereas Tekken 3 was released to immediate, massive acclaim despite similar roster overhauls and gameplay changes (for instance, Tekken 3 removed the ability to simply jump out of all attacks, making the game far more skill based) and introduced the sidestep to put Tekken in the 3 axis-style of fighting games..

The major overhaul came from Tekken 2 to Tekken 3:

TEKKEN 3
RETURNING
Anna
Kuma (different bear)
King (different man under the mask)
Heihachi
Nina
Paul
Yoshimitsu
Lei

NEW:
Bryan (borrowed heavily from Bruce's moveset)
Eddy Gordo
Forest Law (borrowed heavily from Law)
Hwoarang (borrowed heavily from Baek)
Gun Jack (different moveset from previous Jacks)
Jin Kazama (mixed Jun and Kazuya)
Julia (borrowed heavily from Michelle's moveset)
Ling Xiaoyu
Mokujin
Ogre
True Ogre
Dr. Bosconovitch (joke character)
Gon (joke character)
Panda (skin for Kuma)

Not only is the roster slightly smaller than Tekken 2, several of those characters are either jokes, skins or evolutions.

A key feature of Tekken 3, which I believe helped it to be so successful is that the movesets carried over: Bruce, Kazuya, Jun, Law, Baek and Michelle all had successors in the game which allowed for a great deal of adaptability and allowed more easy access for players who had mastered their characters in Tekken 2.

So what can we learn?
There are a great deal of similarities between MKX and T3.

The roster overhaul in MKX will likely be a huge one, with as many as 14 new characters. Tekken introduced a similar overhaul and also introduced some tweaks to the gameplay, similar to MKX. However, in utilising successor/descendant characters to keep movesets similar, T3 achieved a sense of consistency despite the overhaul. While MKX will change inputs, all reviews and hands on impressions report that it remains similar to MK9: The Kombat Tether reporting that after a few minutes, you adjust to MKX from MK9, very similar to the change from Tekken 2 to Tekken 3.

The design overhaul in both series' lead to a more series, dark game in both cases but this did not provide any real obstacle.

Finally, crucially, is the state of the gaming market. When Tekken 3 was released on Playstation in 1998, Playstation lacked a fighting game to market itself around and had an overall apogee of top notch titles. Furthermore, the fighting game community didn't really have a rallying point: SF3 hadn't been well received and people were sick of SF2 and its series. So Tekken 3 became the premier fighting game titles. Similarly, MKX is emerging into an area where Capcom seem to have seceded the crown once more. UMVC3 and USF4 have achieved all they are going to achieve, and the only next gen fighters are Injustice and KI. What helped T3 become so huge on PS1 was its gorgeous graphics, which made full use of PS1 software: similar to the way next gen MKX is as good looking a fighting game as there's ever been.

What's quite interesting is the way Tekken and SF have gone since their third iterations: SF struck gold with SF4 and is now the king of fighting game franchises while Tekken has never really hit the heights of Tekken 3 again, despite the engine and system of Tekken 6/TTT2 being as good as anything else in the fighting game genre. Both franchises have also taken a consistent approach to their roster, very similar to Tekken 2: only adding a few characters but not subtracting anyone. The problem is that this leads to a massive roster and thus the game can feel overwhelming.

In conclusion then, both SF 3 and Tekken 3 had massive roster overhauls. SF3 went through a few years of being poorly received by the fanbase but eventually it solidified its place in gaming lore. Tekken 3, perhaps learning from SF3's mistakes, kept a lot of movesets in the game through successor characters. Due to other events in the gaming arena as much as the brilliance of Tekken 3, Tekken 3 became a must-have title for the PS1 and is now enthroned as one of the all time great fighting games. Due to the similarity between Tekken 3 and MKX, I predict that MKX will more closely follow the trajectory of Tekken 3 than SF3.

In short, don't worry about the roster overhaul, this game will be awesome.