I didn't see this posted anywhere, but also bare in mind that I have not read any of the threads that contain spoilers so it may or may not have been discussed in there.

As far as I know, none of the following information is really "new", but it did clarify some details about these modes that I personally wasn't sure about, so I thought I'd post it just in case some had the same questions/concerns. Derek Kirtzic is providing the information for the article.

The Challenge Towers - "Reincarnated from MK9 in the form of three separate towers that the studio plans to update regularly. One tower updates on the hour with damage modifiers and event frequency increasing as you climb higher, and another changes each day and provides random modifiers with more chaotic permutations for each challenge. The third is designed around special occasions. This premier tower changes every week on average, and includes holiday and special event towers. Players can choose their character for each challenge."
Here, the article notes that Kirtzic was tight-lipped about them simply saying "You'll just have to see what we have in store."

Now, this next bit is the information that clarified some of my confusion about the Factions. Specifically, OFFLINE players.

Faction Wars - "Every action players do in-game - whether in online or single player modes - earn points for their team. Daily faction challenges such as "Perform five uppercuts today" or "Win two ranked matches" also reward points to the factions with players who complete them." "Kirtzic insists NetherRealm is not abandoning players who enjoy playing offline." (HEYO!!!)

"You do not have to play online or in online game modes to participate in the Faction system," says Kirtzic. "We also want to make sure there's enough content for the people that just like to play single-player and don't like to get their ass kicked online." (V.V)

That about sums up the article. It only covers two pages, and is basically a recap, but that last bit extracted a sigh of relief on my behalf. I was under the impression that you had to be online to participate.

The articles also states that PS3/360 versions will still be available on April 14th. Probably a misprint, but sharing that nonetheless. Also touches on interactables, and the variety in character model sizes. (Ferra/Torr noted)

Hope this was helpful for anyone who still had some confusion on the matter!