The ENTIRE Bran storyline since season 1 is about Warging
If Bran can do it, then his brothers and sisters can do it too
Bran is just more inclined to do it because his spine is broken
Do you think viewers are that stupid ?
They literally showed that nonstop throughout Bran's storyline.
Anyways, that theory is really widely believed and makes a lot of sense. It's either going to be that or that
Melisandre just revives him Beric-style
, although I personally believe that the first option makes a lot more sense and has been led up to a lot more.