What will we not get without Endwalker?

[EzekielBook]

So, when Endwalker releases, there will obviously be changes to the core game, some of which will affect the entire game, old and new.

Obviously you won't be able to play Sage or Reaper, the new classes. But what else will we not be getting?

[ItMe]

Island Sanctuaries
New raids and an end to the main narrative
Upgraded jobs
Ishgard housing
Etc.

[Shougun]

Island Sanctuaries
New raids and an end to the main narrative
Upgraded jobs
Ishgard housing
Etc.

I think they meant without buying the expansion, say for example Ishgard housing is probably going to be regardless of expansion status- since if a FC had ishgard housing and you didn't own the expansion would the game be like "LUL, NO FC FOR YOU".

On the question from OP I think people answered without a lot of points so I'll go generic and simple (but a bit flawed) then:

Anything post level 80. Which therefore would include the gear, quests, areas, and so on that rely on that post level 80 concept.

[Nihility]

Access to any areas that belong to endwalker content
Endwalker jobs
leveling past 80

skills and system will be updated to endwalker state for everyone
anything that's not BoP will be attainable so glamour, new furnishings and whatnot can be used
usually a decent amount of little new things scattered about in pre-existing areas

basically if your not 80 yet, absolutely no need to do it until you hit 80 and decide you want to keep going

[Jeeqbit]

Fixed scaling so we don't skip mechanics as much in old content
New deep dungeon
New hildibrand
New bicolor gemstone farms
New hunts
New treasure maps
New dungeons
New relics
New class and role quests
New collectable quests
New tomestones and gear

[Kahnom]

SCH's Sprint boost.