Well, general talk around here is that Sharon's not coming back politically, regardless of what happens. The doctors haven't even begun to asses how much brain damage has been caused, and there has been brain damage. Either way, the recovery period will be long and hard - IF he recovers - so there's just no future for him in politics.
Now, Ehud Olmert, the interim PM, is probably the most corrupted politician in the government. God have mercy while he's in charge. Anyway, politically, unless Olmert's a Clark Kent, there's no way he's gonna be able to keep the centerist Kadima party anywhere near as strong as it would have been under Sharon. With the elections 2.5 months away, there's not enough time for anybody new to step to the front and take the reins of Kadima. Which basically leaves the question of Peretz (Labor / left wing) vs. Netanyahu (Likud / right wing), and as far as I can tell, that's no competition at all. The only chance Netanyahu has of losing the elections, IMO, is if Olmert drops out and urges all the Kadima voters to vote Peretz... which I can't imagine him doing, since Olmert came from Likud, not Labor.
So, in the end, and in my very amature assesment, Bibi Netanyahu will be PM in 3 months. Which, in my opinion, is a good thing.