View attachment 8062
If there were to be a third row here is how I think it would be fesible. Cut the row length down to 12 from 13. Would need at least 3 secret characters in the game (and there have been many hints to plausible hidden characters, Reiko, Cyrax, Sektor, Fujin, Baraka). Because after the next Kombat Pack I don't think there would be more than 3 more DLC. MK9 had 4, Injustice had 6.
So yeah, a third row might be likely, I don't think they'll hide the kombat pack, secret characters and future DLC characters behind one select button/slot. Especially as injustice they worked it into the overall select screen.
This would make my day. Actually looks like it'd fit, too.