I think Pyro kinda hinted that we'd get the BK5 option on it. I will say I'd be far more concerned with an Me410 carrying MK103s than one with the BK5.
If I'm in a tank, I'll be a bit more afraid of a 410 sporting the BK5 personally.
I know that a Yak 9T can take out tanks if you hit them in their "sweet spots". Since the BK5 IS a better cannon than the 37mm on the 9T, yeah...
Against bombers, I honestly can't say. If it performs well enough, I may take the BK5 to use against bombers from time to time. Chances are though, I'll use it in the AT role.