Could 'Gravity' lose Robert Downey Jr?

Seriously, if Alfonson Cuaron had any luck when it comes to his sci-fi flick, Gravity, it'd all be bad. After months of roadblocks, mostly dealing with actresses backing out of the intense lead role, they finally settled that roller coaster by signing Sandra Bullock(Boooooo.)  The one constant has been the male role opposite her, which has had Robert Downey Jr. penciled in almost since day one.  Well, even that might be in jeopardy now.

According to Deadline, the delays have thrown his schedule completely out of whack. The intent was to start on Gravity, then push ahead with Guy Ritchie's Sherlock Holmes sequel, then jump into the slew of Marvel flicks he's got to be a part of. Well, now Sherlock Holmes is next on deck, and after that it'll be tough for him to find time for anything that doesn't involve a suit of armor. 

For the record, Warner  Brothers says this isn't an issue, and it may well not be. But there's no denying he's got a lot on his plate right now. If Natalie Portman had won the lead role I'd be less concerned about Downey's potential departure.