Sorry but if universes are conformed to maths and maths is complex instant universes are likely.
No, they are still unlikely, it's just that in an infinite chain there will be an infinite number of them. There will huge numbers of more likely universe between each instance, though, because they're unlikely.
The only way we are likely to have any idea of other universes is through maths. That isn't science. They must therefore be unfalsifiable.
No, we have no idea of what future scientific ideas will be able to measure. All we can say is that they are mathematically viable now and that we can't prove (or disprove) them
yet. Even now there are cosmologists with hypotheses on how other universes would measurably impact on our own, and are preparing experiments to try to test them.
The trouble is if universes are defined by maths then if we accept the multiverse we must also accept the possibility of universes not defined by the laws of physics you are alleging are multiversal.
Universes aren't defined by mathematics, universes are defined by natural laws. We can model those natural laws mathematically.
You have therefore been truly caught out fine tuning the multiverse to suit philosophical materialism.
I've not 'fine tuned' for materialism, I've openly presumed materialism from the start and explained why. As ever, all you need do for me to update my idea with 'gods' is to justify anything non-material: you still lack any sort of methodology for justifying anything else.
Even if there were some mathematical shortcoming in our material understanding of the universe, that's a call to update our material understanding, not arbitrarily look for magic.
O.