Virat is important but he is not made for T20. To date RCB has never won an IPL trophy. He is not a captain product as he was one of the worst captain for India in T20. He is good with ODI and test cricket whereas he lacks the stupid expertise of T20. This format is not good for the technically good batter. This format is for the nonsense batter, who only needs timing and agressive attitude. Virat as a batter is not that agressive as compared to a fielder.
I feel he got another opportunity and he would again fail. The same goes for Rohit as these guys are not that agressive as they were when they were young. They are still holding as they grow old, they both should concentrate on other formats rather than T20.
RCB don't have whole squad on same page so they keep losing IPL, you look at current squad they have 4 top tier players (Kohli, FAF, Maxwell, Siraj and now hopefully Green will be a good addition), rest not much. You look at matches whenever RCB won, it'll be obvious that one of them played good.
Rohit- Kohli might not be aggressive as young players, but they have acceptable strike rate for T20, plus whenever these two are on crease, their mere presence helps the team. You remember how Virat got out in odi wc and how much under pressure Rahul came? Don't you see how in last test matches against SA where when Virat got out, and you felt now team is done.