"Test-tube hamburgers"

I think it could, so long as it was cheap enough. It would take a few years first and would have to be promoted a fair bit, but I think it would go mainstream after a few years

Essentially, the cells from one animal could feed billions. I don't see a problem with that. Not sure if I would eat it, but I agree with it.

But... how do they fit hamburgers into a test-tube? (and how do they get them out?)

I think this is a great step forward for animal rights. I only wish it could be developed faster so we could put an end to the slaughter...But i fear the religious sector such as Halal would find some reason to boycott this advancement.  we have a long way to go unfortunately..