The engine may end up being an "Enterprise Mode" like IE I think?
Edge as a browser works well but with a few show stoppers that killed any further usage for us:
1: Downloads mysteriously won't start or just plain stop for no reason.
2: Edge ate my favourites way too many times.
The containerized Edge, Application Guard I think(?), is a great idea. If Edge was as good as they had hoped it would provide a fantastic sandbox experience to protect users from drive-by attacks and bad GET commands from e-mail clients.
At least we are not getting stuck with the legacy ActiveX that keeps rearing its head every once in a while because of IE. :P