Maraudon is the best candidate to receive a 20 man raid.
The whole dungeon is wide and bigger and looks like it can hold 10 or even 20 players.
ST is mostly small and not even bigger enough for a 20 man raid, or to even allow mechanics that they’re likely going to implement.
Source? You’re stating as it is confirmed to be ST while it is not, nowhere any reliable source.
And we were told it would be a 3 day lockout for 20 mans anyway.