If Goodell manages to bring the NFL to Europe, London isn't the only place that could have a chance at holding onto a team. Throughout years of experimentation in Europe, Germany has always had several teams competing, and football seems to have really gained a foothold there.
Through all of the changes with NFL Europe, the Frankfurt Galaxy stuck through it all and enjoyed the most success out of all of the teams. The population is only 650,000, so the market doesn't seem very large, but the Galaxy's past success probably left a strong enough mark to leave fans waiting for another team.
Frankfurt has a surprisingly beautiful skyline and provides amazing scenery around the stadium, which would probably still be Commerzbank Arena, the home of the Galaxy. If a team did end up in Frankfurt they might just stick with the name Galaxy for old time's sake, but the bland logo (not that mine is any better) warranted another shot.
USA Today reported that the commissioner seems to think that Europe could house an entire division of teams, and with better talent than NFL Europe ever had, the second time might be the charm. Still, the NFL would have to find away around huge issues like time zone differences, jet lag, and getting players to move to Europe if they get acquired by one of the teams there.