My personal guess would be anywhere between 300-350 the high end of that assuming an improvement in quality, the low end if it stays the same. But I can't see it climbing to 400, it won't have late legs due to Star Wars. 200 is just trolling.
I can guarantee you said all these things about BVS (except DCEU averaging 300dom since there was only 1 film pre BVS). If it matches BVS dom, they're lucky. You severely understimate the impact being the sequel of an awfully received film will have.