I never understand where this fear comes from. "Content becomes outdated and new players cannot clear because no one is running those things anymore." The only example of that we see is DR and Rival Wings. Everything else has either roulettes to supply that content with players reclearing for other rewards, or a dedicated community that continues to run that content regularly. Like, Eureka and Bozja are not dead. They're not as active as they were at launch day, but you can log in at pretty much any time of the day and find people there. DR's flaw is being a very specific piece of content with little to gain from running and no way of accessing it through any kind of roulette. And even that's not fully dead because there are absolutely communities that continue to run it that a new player can access.
As for meta jobs... That whole "if you're not one of the meta jobs this patch, you might as well not even bother playing..." Have you ever actually raided in FFXIV? Because you could not be more off-base with how the meta has existed throughout this games lifespan. Look at Stormblood where you had things like piercing damage comps. This meta was pretty much just for world first races and speed clear teams. No PF worth its salt restricted any job from joining, and the maybe 4 of them that did because they read on some BS gaming article that DRG + BRD was "Mandatory" and proceeded to treat that as gospel were seen as jokes and not worth joining anyway.
These fears are baseless, especially to the extent that people are asking.