As many serious players quit, trying to keep 30 people in a team can be a real struggle. It would be helpful if we could have an extra 1-2 spots tagged as "overflow", in case one person needs to suddenly drop from the team for whatever reason (rage, illness, emergency, etc.). Wars could remain maxxed at 30, of course.

Yeah, I know, this isn't high on anyone's priority list but could be a simple QOL improvement for war teams.

So if the main 30 is Waring , those 2 extra spot will be empty ?
and when one want to quit it will be moved to those slot and new member will join ? and how this differ from when someone want to quit he just leave or leader kick him and he can apply later at any time ? what is the advantage of being at overflow spot over no team at all ?

The advantage is you're actually part of the team. Cell trading, chatting, and even be in occasional wars. Heck, even let'em contribute to races.

Maybe they could be designated as overflow, or the game could do it's selecting 30 players and have the 2 "weakest" sit out, as the system does already. I mean ideally the AI would do a better job of picking who gets excluded, but I wouldn't hold my breath there.