Nat answered this in the AMA: They intend to develop both, and ensure VSTS users can use GitHub easily for version control if they want to.
But bear in mind, extremely long-term support for business workflows is Microsoft's obsession: Even if they decided to "retire" VSTS, it'd probably get updates for the next decade or so.
But bear in mind, extremely long-term support for business workflows is Microsoft's obsession: Even if they decided to "retire" VSTS, it'd probably get updates for the next decade or so.