So based on the info that Napalm1980 got from the German magazine Man!ac on MKX:

"about the "living Towers". three Towers with challenges awaits us.

one Tower with 5 challenges changing every few hours. another Tower with 8 challenges changes daily and the last Tower with 15 challenges changes only on Special Events."

I actually liked the challenge towers from MK 2011 and I'm glad they're making a return. The fact that there are only 28 challenges at a given time pales in comparison to the 300 challenges in the last MK but I guess the fact that new challenges appear every few hours makes up for that.

I'm very curious about the living tower that only changes for special events. I hope that those are the challenging challenges like the End Game one in MK 2011 or the 'figure out what to do' ones from MK Vita. It'd also be nice to keep the special ones here like when characters receive new costumes (Cyber-Reptile) or movesets (Tremor) on the special tower so we can play and replay those events over and over. And, since this tower only changes with special events, you could have holiday themed challenges (avoid falling eggs on Easter?) or have challenges that sync up with new DLC characters.

I know there's going to be a hell of a lot of repetition and silly challenges that will come up over and over again (headless Kombat, knock-off mini games, anything raining from the sky) but I am looking forward to these living towers and I hope NetherRealm does support this part of the game for at least a decent amount of time.