Osborne will ride this one out as the budget is not controversial with great swathes of voters who have no idea what capital gains tax is and think disability claimants are skivers zipping down the offy in their mobility scooters. And even Tory voters perceive Duncan-Smith to be a weaselly little turd.
Osborne will ride it out so long as he retains Cameron's confidence. If he doesn't he's toast. Right now his future as Chancellor depends on how much credence we can give to reports of a rift between them - and to Cameron's statement that he 'absolutely' has confidence in him. In the longer run this certainly knocks a hole in his aspiration to succeed Cameron as leader, although whether it's a big enough hole to sink him completely is another matter.