unique vortex
People usually have several alts and you're sometimes not sure who you're talking to in team chat.
Could we have something like "(Alt name [Main name]) message" displayed in team chat when someone types a message?
The chat Main name would be entered in Options/Social, in order to be able to shorten it. So, i'd enter "Lab" to avoid having the overly long "Labrador_wow_wow" name displayed with each message.
Maybe let the user select if he wants to display the Main name with a tick box.
eternal aspen
From someone that have 10+ accounts, yeah this sounds like a good idea. But i think it will be limited to 1 char per account and instead of an option box a command setting. Something like this is already in the game when you PM someone, if you switch alts (on the same account) it will redirect the PM.
Using it over multiple accounts (everything that logs in on your client, or a server side thing tjat connects all accounts) will be a lot trickier to do.
coarse slate
The thing about redirecting the PM is it's optional and the other side is not aware where it's redirected. So announcing is not quite the same thing. I don't think allowing users to change their nick is a good idea. I could see alt name (main alt name) potentially but user entering is probably not great for moderation and probably too ripe for abuse. But maybe a team only nickname.
split axle