But, beyond the technology, is there economic meat there?
I'm not so sure. How many different virtual worlds do connected consumers really need? Virtual worlds are hyperpublic goods - the more they are shared and used, the more everyone benefits. The flipside is that the less any single one is used, the less everyone benefits.
So segregating worlds may lead to what we might call an inverse walled garden effect, which is perhaps today's bigger danger: too many hyperfragmented open gardens, but not enough people to really drive liquidity in any single one.