Well Mexico has already hosted it twice since 1970 and the USA has hosted it already in my lifetime, and I'm still in my 20s. How about giving another country a go?
Not to mention the travel times, not just for the teams but for the fans too. Not only is it tiring, inconvenient and expensive but won't there be travel restrictions between the countries?
And don't get me started on the expansion of the world cup, we already get a fair few awful games with 32 teams, there are going to be some serious unwatchables in there, especially with some many players tired and jetlagged from the likely travel times between games.
And if they're intent on hosting it across a number of countries, get on over to the UK!