reminder that LFG does not equal dungeon finder. you will not have instant cross realm dungeons, that will simply not happen, Every private server. classic wow and tbc classic had addons that were LFG tools to find dungeons, this is a good change they are adding.
I wouldn't mind the TBC LFG tool in vanilla. It already exists but requires you to talk to an Innkeeper first...and isn't very good at making groups.