How should the next expansion be handled? For new players/characters?

[Seraphor]

One voucher for a free story skip and job boost included with the purchase of 7.0, which the player can choose to use immediately or save for an alt later.

The story for 7.0 can aim to be a "non-confusing entry point" but should not try to pretend that newcomers are meeting the characters for the first time.

This is pretty much the only sensible compromise I can think of too, and it would be a compromise, in every way it's plastering over a fundamentally unsolvable problem.
Perhaps using this new 7.0 boost comes with a short summary of the WoLs journey so far, an abridged version, that takes place in a 10-15 minute cutscene or over the course of a couple of bonus 'starter' quests. In a similar way to how ARR solved for 1.0's destruction, but on a five-times larger scale.