There are many people who think letting America host the 2026 world cup was a wrong decision and that they will have problems visiting this country to watch the World Cup games but I disagree and I think since America got the experience of hosting other great tournaments, they won't disappoint us and we are going to see a better world cup than what we saw in Qatar.
Obviously it will be better than Qatar and at least there will be no discrimination against unmarried couples and beer will be made available at the stadiums. Hotel rooms will be less expensive and travel will also be easier. But none of this matters, if the fans are unable to get a visa. Anyway, we have 3 years to go for the start of the tournament. Hopefully we will get some clarification regarding the visa issue by then. BTW, a lot can happen in three years. POTUS election is scheduled in around one and half years, for example. It's outcome can have a huge impact on the visa rules.
I think there will be special visa cases for this situation. I have seen Istanbul visa for this years UCL finals and they only ask for a ticket, nothing more, if you have the ticket they give you a visa for 3 months, the game is just one night. If it's the same for world cup as well then people will be fine, and yes I get it, it's easier to get a visa to Turkey than to get one for USA I assume, that must be true, I have never tried it for both so far so I can't really say, but it does make sense if that's like that.
But if you get just a single world cup ticket, and a hotel booking ,showing those two should be more than enough and you will probably get a visa. They will not have a reason not to take you in unless you are a criminal or something, it must be easier than normal times.