correspondence chess

how about a chess.com team involved in friendly matches with other online chess provider and see who has the best players. or a rated international match with iccf..... 

That would be hard to do but it would be fun.

that should be the essence, to have some fun. and also this may established who really is the No. 1, because everybody is claiming that they are No. 1 online chess game provider.

This does go on at other places.  I believe Schemingmind, ICCF, GameKnot have all done this.  If Chess.com does it I would suggest only Premium members be allowed to play as they have invested in the site and are less likely to just drop out of a match.

premium members or not, but the selection should done in a tournament based championships, and whoever finishes on top should be a shoo-in for the team that will compete with other web servers.