The last 2 is because COVID messed up the Nations league schedule. The finals were always supposed to be in the spring, but because stuff got delayed there was a cascading effect and we had to have the finals in the summer twice. That put 2 tournaments in the same summer and we prioritized Nations league. Going forward this won't be an issue as the Nations league final 4 will be in the March window.
This Gold Cup in particular will be big because CONCACAF is expanding the tournament and inviting teams from other confederation as a world cup walk rest run (similar to what used to happen with the confederations cup RIP). The exact details haven't been finalized yet, but I would except a 24 team tournament with 16 CONCACAF teams and 8 guests (probably 2 each from the non Oceancia confederations).
I doubt the big euro teams come, but I could see mid level (Switzerland, Croatia, Belgium types) and I bet we get at least one of the big 2 south American teams, but we'll see.