We've already got theories which say that the universe is spatially infinite and quantumly branching. One more level of infinity on top of that isn't going to m

We've already got theories which say that the universe is spatially infinite and quantumly branching. One more level of infinity on top of that isn't going to make much of a difference. I suggest you regard all events not part of your decision-theoretic future (those you have no influence over) as part of the generalized past, and ignore them.