~snip~
The quality of the stadiums and any other facilities should be obviously higher than the last world cup we saw because four years passed and we can have better technologies for stadiums and this can definitely help the hosts, while in some countries they don't have a good financial system like Qatar does, they can't provide good quality facilities if they don't already have enough facilities.
Well, 2 out of the 3 countries have already hosted the world cup in the past, Mexico and the US. So basically there's a big chance they would just be reusing their current infrastructure.
I don't think they're going to spend too much making new stadiums or renovating old ones.