It is somewhat obvious that what they say that when the World Cup ends, some will want to stay there as illegals , in any case, there are many citizens of other countries who are in the USA and work, taking care that the police catch them and deport them, as far as As far as I am concerned, I think that this will be very difficult for the USA to control, because there is clearly a lot of migration, from Venezuela they go to Colombia and they prefer to go through the Darien jungle, which is so dangerous, but even so they are looking for the American dream, now if they put As a resource for the World Cup, they can easily stay in the USA with many Excuses, and since the US elections are coming in 2024, it will be Interesting how they are going to handle this.
Interesting concern but I believe that if anything, the USA knows how to handle these backdoor (illegal) immigration problems. They have had a plan ready probably by the time they submitted their application even when in the meantime a good couple of things changed. When they calculate the risk potential for people to come as fans with the intention to stay in the US, they know that it is happening either way and such an even won't really drive those numbers up. You could say the same of other sports events that happen near the boarder. These alternative routes as you mentioned through that jungle are hard to control not only during a World Cup, but at any time. The police presence will be significantly increased due to terrorism potential alone. It might not even be the best time to go for it as an immigrant from that perspective.