The moment when they said we were going to have three hosts I was thinking how the palyer and fans were going to travel between these countries because even if we consider these countries are close together there is some paper for the people who want to travel between these countries and this can be annoying for people.
I think the best they can do is to make some special rules during the World Cup regarding this.
Certainly the most complicated visa to opt for will be the American one, the others are easier.
I can't say how it is in other countries, but in my case, as a Brazilian, I've been verifying that fortunately 85% of people managed to obtain a tourist visa last year.
With the American visa in hand, as a Brazilian, I manage to obtain authorizations to enter Mexico and Canada with much less effort....
Authorization for Canada consists of applying for the etA, an electronic authorization for travel to the USA, which can be easily obtained on the Canadian government website.
To enter Mexico, you don't even need authorization, just present the American visa upon arrival in the country.
In any case, I hope that these countries make it more flexible for tourists to enter other parts of the world during the World Cup.