It's weird because all 3 of these July flicks have a "wilcard" quality to me, where they could each go either way. I could buy any one of them just completely falling off a cliff just as easily as I could buy any one of them wildly overperforming. But if I'm being honest with my actual prediction, I think IF all 3 are at least decent, they will all do well, while maybe not quite as well as their respective fans are expecting.
The JWorld franchise a textbook example of diminishing returns while still being successful, so I'm sure it will bring in big bucks, just not quite as big as it's predecessor, and it's a franchise with big 2nd weekend drops, so I doubt it will hurt Superman too much unless it has amazing WOM. F4 is an IP the general audience doesn't give a s*** about, but the movie looks different enough from Marvel's recent failed efforts to bring people out for it that didn't come out for those, and GotG proved pre-existing interest in the IP doesn't matter so much with Marvel. The IP is Marvel itself, and GA interest is gauged by how it looks compared to other Marvel stuff. So I think barring a terrible misfire, it will have a respectable run. Superman is an IP the general audience cares for more than F4, but less than Jurassic, and the GA have also been onboard with Gunn's previous family-friendly fare, so I think - especially with Krypto in the mix - this one will have the biggest appeal to families of the 3, so it should also have a solid leggy performance if Gunn delivers on the level of the Guardians flicks or better.
I kinda expect all 3 of these movies to end up somewhere between $650-925 million each, with Jurassic being the highest unless it royally sucks. And if Superman falls anywhere in that range while getting good critic/audience scores, that's more than good enough for a sequel and a solid start to the DCU.