On the topic of current UU bans, I would struggle to say both Kyurem and Victini are broken without their respective weather, as they both lose a vital power boost (Blizzard for Kyurem, and the power boost to V-Create for Victini). Although, I can see them banning Kyurem rather than Hail, as banning Hail removes an entire viable playstyle from the metagame, while Hail isn't really that bad without Kyurem. Drought, on the other hand, is ridiculous. The amount of Pokemon which abuse this without being broken out of permanent sun is insane. I really can't see this hanging around in UU much longer. I can see ShellPassing being banned though. The ease at which you can set it up, and then proceed to sweep, is close to moronic. I will be very surprised if this remains in the current UU metagame.
Keldeo will almost certainly be OU. As d0nut said, it's an incredibly effective CMer, as with a set of Hydro Pump / Hidden Power Ghost / Mystery Sword / Calm Mind, it can break through almost all it's checks with minimal entry hazard support. The major checks I can see to it would be the Lati's, since both would likely outspeed, resist both it's STAB's, and either OHKO it (Latios) or proceed to set up alongside it (Latias). Considering they both have recovery, I can't really see Keldeo winning a one on one situation against either. Considering this, it's likely Keldeo will be partnered with a Tyranitar, as it can easily switch in and proceed to Pursuit it's two major "checks".