When there is money, befitting stadiums could be fixed in 4 years, they will only need to employ more labour and expertise for the job. And it's not that they do not have some good stadiums already, they would only renovate one or two or three, building from the beginning might not be necessary. The burden is more on the shoulder of the US, and I know they would deliver.
Also, the host countries (US, Canada and Mexico) are not extremists like Qatar, so I don't expect many limiting rules. And as for travelling, there is no way it would be convenient for every interested people. Some countries would issues visas, while some would deny them, and some viewers would naturally be discouraged financially to be touring all three countries.
We know money can socle many problems the in the past world cup in Qatar they could easily provide the sports facilities, stadiums, and hotels without problems because they had the money because Qatar didn't have enough potential and they have to spend too much money while in the next world cup in 2026, I think other world cup hosts and especially America got enough potential for hosting the world cup and they can host the world cup better than Qatar.