~snip~
I think it would certainly help smaller countries or countries with no economical resources to host the whole event to still be part of it. They would not need to invest so much in infrastructure, security or places to keep tourists happy, since all the event would eventually move to a neighbor country.
For example, Nepal and Mongolia are counties that by their own could not host a World Cup but they could if decided to co-host with China.
Of course, all of it would not be that easy, there are neighbor countries which have political and ideological disagreements among them, which would not allow them to coordinate such big event as orderly and quickly as it is supposed to. Whether we like it or not, when talk about more than one country, we need to think of geopolitics.
True, but still I think it's best to have the world cup in a single place. There are so many issues that appear when you host it in multiple countries, and also each country has it's own rules, and laws, visas, etc.
And at the end of the day most of the games will be played in the US anyway, so I'm not sure why Canada and Mexico wanted to be there. Maybe Canada wanted to finally be able to host it, but the other two already have done so in the past.