It's been a bit and I wanted to refresh myself by doing new game plus and going through all of the MSQ in time for endwalker. I've never done new game plus before though, or know how long the MSQ is altogether. Is it possible for me to get through it before endwalker releases?
In New Game +? Plenty of time, since you don't need to level.
Being Lv80, NG+ will go much faster for several reasons:
- You don't have to take time to level through the story's level gates
- You can solo most duties so that the duties themselves only take one or two minutes
- You will one-shot many overworld quest mobs
- You will be in max IL gear during the solo duties with compulsory sync
- You can already teleport to all sanctuaries
- You can already fly in all zones
So instead of any of those being a major limiter to your progress speed, it's mostly just about how fast you can read dialog. I imagine with all of these things in your favor you could probably do a refresher run of the entire story in two weeks.
A few months back, I created a new character that played solely though MSQ plus what I considered essential side quests (job quests, aether current unlocks), reading all dialog and watching all cutscenes. It was 170 hours of time played to get to the end of 5.0.
With the all advantages available to you that Rongway mentioned, you'll be able to complete it through NG+ faster.
Even doing a fresh character, sticking solely to MSQ I'd say it's plausible. Depending on how much time you're willing and able to invest, at any rate.
There've been many changes behind the scenes to the leveling / questing experience long-term players wouldn't notice, since this game doesn't require a different character for every class (so there's no real incentive to play alts). A Realm Reborn was revamped and made significantly shorter, especially in the 2.X era (though this came at the expense of some great moments, like the sylph impression of Thancred not wanting to go fight Ramuh for fear of damaging his beautiful face). Though Vesper Bay still lacks an aetheryte, you're given a set of tickets that will teleport you straight to the gate so returning to the Waking Sands isn't a great big chore.
More generally you're given EXP far in excess of what you'd need to hit the level cap for a given expansion, so EXP gating is practically nonexistent. (Which is also helpful for picking up 4.0+ Jobs ASAP.) #.X patch quests give tokens that can be redeemed for gear appropriate to the content you're headed into (e.g. 2.X will give Gerolt's Masterwork pieces). Even on a fresh character the only issues there really are, is certain regional Aether Currents being a pain (though you don't need to get them all - I skipped The Lochs on Trpimir here), needing to gear up for 5.X content (which shouldn't be too much of a problem, given Exarch gear is dirt cheap on the MB), and having to do the Crystal Tower series prior to 5.3 (which is also not much of a problem, given those raids take almost no time at all... or would, if people were smart enough to learn / remember Angra Mainyu and Cerberus' mechanics).
On NG+? You can fly off the bat (even in 2.0 areas), you don't need to worry about gear, and if you're waiting for Endwalker I assume you've already done 5.55 and thus have CT done. So it's really just a matter of how fast you can fly around, watch cutscenes, and curbstomp all non-roleplay battles.
All of MSQ? Even at level 80, I don't think you have enough time to do it in under two weeks.