Honestly I’d think it would be great to get all starting zones redone as it really fleshed out the Races. The Starter island is just lazy.
The Forsaken should start in northrend as a newly freed undead rescued by the forsaken. They could have a cool quest alongside Voss as they free more undead. Show Banshee, liches and Nerubians joining the forsaken. Could flesh and explain what happen to them in the past with Arthas, Sylvanas and the Jailer and their ties to Shadowlands.
The Night elves should start as a Member of the resistance in Hyjal as they are rebuilding their home there and working to push the Horde(old sylvanas loyalist faction) out of their lands.
You could even let older players do this content on their characters.