Hello, I have few friends who want to try the game when the expansions release. But there something i am afraid.

When they reach 50 with the main quest, they will be stuck with doing the 50+ quests of 2.x to reach heavensward, to do all primals and dungeons.
With all existing players doing heavensward, nobody will queue for old content, so the queue will be longer.

It's kinda bad to block people at level 50 and not allow them to reach the expansion considering theses quests doesn't take just few hours.