I think it could be cool, but the difficulty is currently set for 4 players. It would be an entirely different game then.
If they would create forrest area where everyone could run around killing booma's and talking to each other, You would have such a game.
The one thing is when you reach the edge of the forrest you should face the boss with a group of with a maximum of 4 players. Facing the boss with 20 players would be to easy. A transporter with 4 entries could do the trick.
When you defeated the boss you will earned the right to move on to the next area.
Maybe they could use this idea for PSO4?
Only the needed servers will cost more than the current. Who want's to pay a higher hunter fee.
Also it should be possible to convert the current savegames, if they want people to step over to a new version.
Let's see what happens in the future