I think it's just an assumption by fans that the plan is to have him win at All In. When he started the program for the International title last month, I assumed that was the excuse to keep out him out of the World title match at Wembley so the fans would kill their assumptions lol
Now I'm thinking they go one of two ways with it...
He loses at Forbidden Door, but they add a New Japan or CMLL guy to make it a Triple Threat so Ospreay doesn't eat a pin. Ospreay defends his International title at Wembley like he was going to anyway.
or
Swerve goes full heel again, beats Ospreay with some shenanigans, they run it back at Wembley. Maybe we'll get lucky and they'll merge the International title with the World title and have one less title on the show lol