In cosmology, can we still distinguish between science fact and science fiction?

I'm a great admirer of the technology and the advancements made in the awe inspiring fields of astronomy and physics, but it does seem to me that theorising about the probable has largely been replaced be hypothesising about the possible. I refer to parallel universes, the many quantum worlds, anthropic universes, holographic universes. These ideas are of course fascinating in there own way, but appear to be unverifiable by science, and yet popularised by very knowledgeable cosmologists. Will they remain ever more only the stuff of science fiction? They can't all be right, can they?