Are there any grounds to doubt?
Yes, there are. The vast majority of the dead in Christ shall rise at the trump of Christs return. She is just as likely to be in that crowd as any. Any opinions to the contrary are mere speculation. If you have any Bible verses that explicitly state she is in Heaven this very minute I would be glad to look at them. I really don't see where this one persons location at this time should merit this much attention when there are so many other things to worry about or do.