I think it's safe to say that some kind of major re-work, as dramatic as the one that turned her into what she is now in 2013, is impending at some point. I really doubt that Kat as she is now, the manaless AoE mage, is at all consistent with whatever the originally envisioned for her.
The best case scenario for me would be that they make her very difficult to play but effective when played carefully and watchfully. Then noobs would have less success with her and stop picking her, no one would bother banning her anymore, and I could actually play her for a change.
Edit to add that if Kat is "OP" it's because her kit punishes the low-level JRPG playstyle (where you just stand there and take whatever the enemy throws at you while throwing your own abilities back and hoping you keep winning the trade) like no other. Kat's ult isn't like like Leona's or Garen's where you'll take some damage if you can't avoid it but chances are you'll still be very much in the fight unless you were already very low on health. With Kat, you HAVE to react (either get away, stun or silence her if you don't have to run towards he to do it, or join in a team effort to quickly erase her) even if most of your bar is left or you will pay dearly. THAT is what low-level players simply can't deal with. And frankly I'm annoyed that the average player is so unbelievably incapable of handing champion whose ult can't just be shrugged off but is otherwise easy to shut down or get away from when she has no CC and has to hold still while doing it.
But what if you're low on health? You're doomed, right? There's nothing to stop her from jumping on you and killing you quickly once you're in range. True. That's Kat, but that's also a long list of other champions. With Karthus, you don't even have to be anywhere near him.
Of course, how is anyone going to ever learn to deal with Kat if she's banned from every game?