I have been reading the Sword Coast Adventurer's Guide. It mentions some of the former Silver Marches communities but not Everlund, Deadsnows, Quaervarr and Newfort — they don't even appear on the map. What happened to them between 3rd and 5th editions?
Deadsnows, Everlund, and Newfort certainly aren't gone, and Quaervarr probably isn't either. Chris Perkins, principal story designer for D&D's 5th edition, was asked almost exactly this question. His reply is that cities not given an entry in SCAG weren't shown on the map either, but it doesn't mean they're gone.
Deadsnows, Everlund, and Newfort are all featured in Storm King's Thunder, albeit with brief entries.