People have been talking about multiverses as a philosophical idea for a long time. But the current incarnations in physics, I think, are more indicative of problems with some things going on at the frontier of physics than ideas that are gonna last.
The Greeks, with their truly healthy culture, have once and for all justified philosophy simply by having engaged in it, and having engaged in it more fully than any other people.
Philosophical knowledge is the knowledge gained by reason from concepts ; mathematical knowledge is the knowledge gained by reason from the construction of concepts.