-Nothing that I know of, but given the events that took place during the Elven Crusade and the defeat of House Dlardrageth, I'd assume he is no longer there pre-Spellplague.
(A Tri-Partite Arcanist Who Has Forgotten More Than Most Will Ever Know)
-The Elven Crusade and the defeat of the Fey'ri was in the Last Mythal Trilogy. Long story short, Elves from Evermeet went to war against House Dlardrageth and reclaimed the ruins of Myth Drannor.
-Since nothing actually mentions Vaerilmor Floshin specifically (other non-Fey'ri members of the Floshin family are), so it's really up to you. You can have him still there. You can have him get killed during that conflict. The Shades from the City of Shade are in the general neighborhood as well, so you could have them get involved somehow. The world is your oyster, really.
(A Tri-Partite Arcanist Who Has Forgotten More Than Most Will Ever Know)