Friends of mine, new to the game, becoming discouraged by STORY QUESTS

[SDaemon]

It's just that the next expansion will have its own separate story requirements that won't include the Ishgard part. (But of course, the next story also won't require unlocking Dark Knight or whichever you're interested in. You'll be able to skip the 2.x patch quests only if you're willing to forego everything that's gated behind them, which is basically all of HW except for the Au Ra race.)

I still see them having to "progress" in the 3.0 story to go into the 4.0 story. Its just you view a recap cinematic rather than play through the quests/content. Its the only way to make things logically flow from 2.0 to 3.0 to 4.0. Because if the story went from 2.0 to 3.0 OR 2.0 to 4.0 it wouldn't work. The ending plot of 2.0 doesn't leave any room except for 3.0 to occur.

You contradicted yourself there. If (as I agree is most likely) the next expansion raises the level cap again and goes from 60 onward, then it too would give you a level cap raise, and HW will no longer be the only way to get one. ARR goes from 1-50, HW goes from 50-60, lets assume 4.0 goes from 60-70. That would mean someone with just ARR and 4.0 (but not HW) would have a level cap of 70 (which 4.0 gave them), but their content would go from 1-50, then have a gap before it picks up again from 60-70.

That wouldn't be the ideal way to play. Generally, they'd ask "how do I get through this long empty patch from 50-60?" and be told to get HW so they can have a full expansion worth of fresh new content while they do it. If they take that advice, then nice for SE, they get another $10 or $20 bucks out of it that way. But if the player doesn't take the advice and keep just ARR and 4.0, then they have to level from 50-60 on just the level 1-50 content. Quite a slog, but there is a lot of level 50 content, so it's certainly doable.

That isn't a contradiction. That is a flow. HW raises the cap from 50 to 60. 4.0 would raise the cap from 60 to XX. One precedes the other as a prerequisite. You are assuming just by buying 4.0 that you could level from 1 to 70. Using your idea they would have to design content in the 4.0 expansion specifically to level from 50 to 60 to accommodation a larger level gap rather than utilize the content they have already developed for that purpose.