Personally I’m hopeful for the day when Edge becomes default. I believe it’s still able to use the older engines for compatibility, but not having to code for Trident for default Windows users would be so nice!
(Chromium) Edge has an "IE Mode" where it uses Trident for specified sites. Very clearly the move here is to get enterprise clients using Edge internally, as it means they have a modern browser on the public web but can maintain compatibility with internal IE-only systems.
I expect Trident is a very long way from being killed, if it ever is. I expect it'll remain around for much the same reason as many of the old Windows APIs have.
