I mean, if they really wanted to do it, there is always a way to muddy it up for no reason whatsoever and to do it just to do it. The Reevesverse's inevitable fate will end the same way Nolan's did: as a standalone finite universe that has a beginning, middle, and end, in the vein of a visionary director who wants to tell a specific story in a specific standalone corner of DC Films. If Gunn truly does respect his fellow compadres wishes, he would leave Reeves alone and allow him to end his vision on his terms. It also buys Gunn time to not have to worry about Batman at this very moment where he can sorely focus on his Superman first and foremost. By the time Reeves finishes his Elseworlds take, the second chapter of the DCU will be right around the corner where the timing would line up perfectly for a brand new Batman.