Considering Mortal Kombat seems to have a pattern in its releases (at least I see one), I would at least hope the next game is their compilation game. Well, first I should probably mention that pattern:

Game 1 introduces mechanics as the start of the generation (MK1 as the digitized sprite-based fighter, MK4 as the 3D fighter with the implementation of weapons, MK9 as the 2.5D fighter)

Game 2 refines what came before and is the best recieved (MKII being considered the definitive sprite-based MK, MKDA being the 3D game with the most room to breathe in development time, MKX with its tightened graphics and bigger profile)

Game 3 adds a bit extra, though has an aspect that is derided on release, with a story or boss that immediately follows from game 2 (MK3 had Shao Kahn carry over as the boss while getting flak for the exclusion of Scorpion, MKD took place immediately after MKDA while people criticized it for being too similar to prior with mostly forgettable new characters, MK11 starting its story mode immediately after MKX while criticized for crunch during development as well as grind and microtransactions)

Game 4 is a compilation game which is a bit rushed (MK Trilogy, MKA)

A spinoff game which is generally not well received (MK Mythologies/Special Forces, MK vs DC)

The cycle starts again

Okay, with that ridiculousness out of the way (I overthink things sometimes), I would think (and hope, actually) that the next game is a compilation game. However, I would also hope they get enough time to refine it, and I would say that they could do it by having a normal-sized roster to start and then begin introducing every fighter from the series who was not on that roster as DLC over time. Yeah, it would make the compilation game have the longest post-release development time, but it's just a thought.

As for the story, I would imagine it could be that when Liu Kang first tries to create a timeline, he accidentally merges the classic timeline with the MK9-11 timeline, and this could possibly be something that causes Armageddon to be triggered in the new timeline. That is, if Blaze would still be the final boss (but maybe he wouldn't be--it would be interesting to have boss-Blaze and non-boss-Blaze as different characters, so the new timeline not having Armageddon triggered would be something to see), but having a new boss step up could still happen. Maybe the amount of fighters could be too overwhelming for Liu Kang to deal with when trying to come up with a new plan for a timeline and he has to fight alongside his friends to try to take down the final boss (who might probably be another titan).

But what do people think? Anybody have any ideas how such a game could be done? Think my assessment of the pattern of releases is too silly (not the purview of the thread, but still, valid point)?