So I just got my second GPU and I was wondering if this game will ever support Crossfire (dual GPU).
Multi-gpu is generally something supported in the driver itself, but may have optimizations added by the game. If AMD supports it you should be able to see a notable improvement just by having a second GPU.
It seems to be detected by GPU benchmarks, but not by Overwatch itself.
Then AMD’s drivers themselves likely do not support overwatch [for crossfire].