How To Access expansion if no one is doing Story Quest anymore?

[Zari]

These dungeons are still being done as others have already pointed out. However it is possible depending on your exact circumstances that queues may be long.

Going in as DPS can be a wait of 10-20 minutes, even at peak hours. If you're playing at very odd hours expect longer waits, but generally no more than 1 hour even in the most extreme cases.

However all of the old content needed to go through the MSQ and even the optional content like Relic Trials is still very much alive. If you're finding it impossible to get in and finish the content something strange is happening to you specifically, rather than a more general issue with the game.

Maybe they play on a very low population server?

[HPDelron]

Maybe they play on a very low population server?

The Duty Finder is cross-server as I understand it, so presumably individual server populations should have little to no effect on queue times unless the game is using some really odd approach to construct parties.

[Niwashi]

Also remember that Qarn is an optional dungeon outside the MSQ.

Well, initially at level 35 it's optional. But then there's a level 50 MSQ that requires it, which is where the OP is at.

(Yeah, I'm not entirely sure why a level 50 quest requires a formerly optional level 35 dungeon. I guess SE must have decided they needed more people doing it. The leveling roulette will only include it if it's been unlocked, so adding it into the MSQ makes everyone eventually unlock it, thus putting it into everyone's roulette, at least once they get that far.)