I think it's also because the attractions will come in the second wave. So 2020 (when they are seemingly doing this big tri-park marketing push) will literally just be DLR anchored with Guardians and the new land (shops/M&G's). Hong Kong with Iron Man Experience and the new Ant Man attraction and Paris with the redone Iron Man's rocking roller coaster.
We know Paris and Hong Kong have Avengers attractions coming that the press release also glosses over, because they likewise won't be open for 2020. The same presumably for the Avengers E-ticket in DL.
Importantly Chapek 'announced' an Avengers and Spiderman attractions at D23. The fact the press release states Avengers and Spiderman are joining the Guardians is reassuring that's still the eventual case.
It's kind of nice that we have four different parks with the same concept but wholly unique attractions. Worst case scenario Avengers in shared but there will be two different Guardians, two Different Iron Man, an Ant man and Spiderman attractions.
Sofar to give a list
HKDL
Iron Man Experience (Simulator)
Ant Man and The Wasp dark ride (replacing Buzz)
Avengers attraction (presumably)
Paris
Iron Man RnRC replacement
Avengers Stunt Show
Something else (Lights, Motors, Action should be numbered for an additional attraction for Marvel and for use in regards to Star Wars)
DCA
Mission Breakout
Spider-Man Attraction
Avengers Attraction
If anything, I am thinking DCA and HKDL share the same Avengers Attraction while Paris gets something like Black Panther or Doctor Strange as an exclusive for them, considering that ToT is safe from Marvel presumably for Paris.
As for Orlando and what they could do after Guardians is one of two other paths.
The first, is Doctor Strange as it seems that he is safe. The other, is Big Hero 6, and while not as likely as DS, it could still bring some audience.
There is a third for Orlando, to where they go into talks with Universal on a deal for Black Panther and Thor park rights in exchange for Fox IPs like Simpsons plus Apes, and Foxs entire Animation catalogue, but I find that more doubtful than anything else