I don't really see any point in doing this, other than the basic principle of letting the highest bidder (city) organise this, in which case it will be hosted in Shanghai or Dubai for the coming 10years
Ultimately what NFL wants is more exposure in foreign markets:
MLB has the 'classic', -which being dutch I greatly enjoyed-,
NBA does exhibitions, pre-season and even early season games abroad,
NFL has the NFL Euro league.
I think the NFL Europe experiment was fun for the NFL fans in Europe (and there are plenty) but it was never going to compete with European football. I doesn't even compete with Eurobasket etc in terms of interest from the public.
The NFL has also had long standing ambition to expand the league with Europeans franchises, but the interest generated so far has not been enough. If they were to expand, hosting a Superbowl in Europe would make slightly more sense.
I must say that I always try to watch the Superbowl, even if that means foregoing sleep, as kick-off is usually just past midnight local time. That alone is a major obstackle for international interest and similar problems would arrive for the US public if the game were to move to Europe or Asia. It's just not practical: 11PM in Paris is 2PM in LA.
But since I play basketball and have friends who play baseball, I must admit that I'm probably more open to US sports than most sportsfans here.