At least there is a really good chance that these flat earth people will disappear once we have commercial spaceflight available in the not too near future. Most likely they will just create a conspiracy theory about Mars or something. Like how they think that Mars is actually inhabited with aliens or something and that's why the average joe hasn't gone there yet.

I really can't wait to see the reactions of flat earthers on various flat earth youtube channels once commercial spaceflight becomes common. That's going to be hilarious! Who knows a lot of them might end up deleting their flat earth content.