TBQH, I don't see Gitlab lasting too much longer without an acquisition event of some sort, when facing up against this sort of Microsoft-backed feature funding. And I say this as a bigger user of Gitlab than Github (primarily because of the free private repositories and organisations).
In the long term we'd probably see the cloud providers create their own social revision control projects, and then fuck around with private APIs so the quality of the integration between their cloud service and their source control leads you to stay locked in.
Even in that scenario it could make sense for there to be a 'neutral' party like gitlab, though.
I acknowledge this is my own imagination and I've no claim to know the future! :)