I never saw this one mentioned anywhere, even though it always seemed the only spin-off that wouldn't be pathetic or lame. Be prepared for:
Seinfeld: The previous Generation In Stereo Starring the elder Seinfelds and Costanzas
As most everyone over 20 discovers, you are becoming your parents. Nowhere is this more evident then with Jerry and George, although the seem clue less to this. So the personalities, idiosyncrasies and style of Seinfeld would be preserved in the new show. However, being from a previous generation opens up whole new territory to explore. For instance, they not only got married, but stayed committed. For life. No mater how nuts they make each other. That's something none of the original 4 could do, ( maybe George could, if it were for spites sake) .
Another difference is on Seinfeld everyone wants to slack off and hang around. That's all the retired have, and are desperate to do anything else. Do you know how often my retired neighbors cut their grass each week? each DAY? Also, where George and Jerry are friends, their parents can't stand each other, and would hopelessly be trying to get away, just to find themselves intertwined. Maybe the Seinfelds could be constantly moving to retirement communities around the country to escape. Of course, I hope in this last episode all characters die in an explosive inferno, leaving no one alive, no mater how incidental or small a part they had in the last 9 years. That's the only sure way to keep greedy networks execs from milking the Seinfeld cash cow with shows that aren't the grade A prime cuts that the original is.