The biggest issue with this game is not his balance, every fighting game has balance issues (since Dhalsim in Street Fighter 2). Every game has one character that is stronger and easier to use and some other that is weaker or harder to use.
That could be overlooked if it's not totally overwhelming.
But when the core mechanics in the game doesn't work, that is a really big problem.

•Targeting system is flawed when trying to change targets
•Revege doesn't work (like at all)
•External indicator doesn't work well
•Tracking in heavies and GB is extremely high for some characters
•Absurd hit boxes that doesn't apply correctly
•Bots that overlook game rules to their advantage (fake difficulty)

And Ubisoft seems to ignore all of this, believing that with some changes to some heroes the game will work.

I don't think the game will die because of this, but the player base is dropping, at least in console (PS4), and before someone throw some numbers at me for saying that, let me say, these days I play against the same player over and over, something that didn't happened to me before.
And that's not a good thing if Ubisof is thinking in a sequel, as we all suspect.