Interesting idea, althought this kinda leaves the question how Rex ended up like he is in the Movie, given that his toy is this: www.youtube.com/watch?v=J0GJzC…
My personal theory for such a scenario, when I thought making one of those toy comics on my own, was that a toy becomes active once it is unpacked. Developing a personality similar to the base character is quite common, but not neccesary. It's most likely when it is the only toy based on a specific character.
Ofcourse, chcaracter development is still possible. So if Rex started out as a the DR T.rex, he must really have been traumatized to end like that.
On the subject of Buzz, I think that works more towards my theory, given that they all tend to think they are the real deal. Also, wasn't Buzz reset at some point?
As foir Barbie, I figure that once activated, putting the figure back into the Box won't deactivate it again. They probably managa to somehow get back into their packages themselves.
It should however be meant that while my planned Toycomic has the whole living toy thing, they were not meant to be like in Toy Story, but rather their own thing. Characters are also aware that they are in a toy comic.