They shouldn't release PTR D.Va imo. That will be a mistake.
Thankfully, it seems that they are looking to experiment with both D.Va and Roadhog at the moment. I'll find the developer posts on the B.Net forums, as it was interesting to see that they are testing out 300/300 D.Va and Roadhog having some adjustments with Hook 2.0.
Probably
You have to remember, this is a class based shooter. If you look at its TF2 origins, Soldiers are pretty much required at all levels same with medics. If you look at MOBA origins, there's a reason certain heroes maintain high pickrates throughout the entirety of the game. There's a reason Pudge is popular.
The only overlap that I really see that I don't think they thought through well is 76 and McCree. McCree specifically.
True, but I wished one of the other Tank Heroes could fill Reinhardt's shoes and otherwise be a fine alternative. Apparently, Winston's bubble shield worked great for choke points during the Beta. And Soldier: 76 was supposed to be the well-rounded character as a solid introductory Hero for those who are new to Overwatch (but are otherwise familiar with playing FPS's). Supposedly, he was much more balanced during the games launch.
McCree, however, I can agree with. McCree was designed in mind to effectively kill mobile heroes & be an anti-flanker, and he's kind of okay-ish at his job? I think Blizz need to actually decide what to do with him and when they do, they should really revamp his abilities to actually get the aimed theme they are going for.