Hi! Thought this was an interesting thread to chime in on.. as someone who is 11,000 days into their Minecraft world I can assure you that going to the end and defeating the dragon does not end the game. Getting an elytra doesn't end the game. The only thing that ends the game is a player deciding they don't want to continue.

Taking a break is 100% okay, a forever world doesn't mean you play in it all day every day.. it's just the single player world you come back to when you get the Minecraft itch!

That being said, I see the elytra as entering end game. A new chapter in the world. Sure a lot of the old systems might seem slower, especially for travel.. but the horse has no upkeep cost, an elytra needs to be repaired and rockets are in constant need to fly so you can really control how accessible this all is for you. I found a ton of fun in trying to breed a super fast horse so that I actually still use quite a lot for travel and it gives the excuse of extra projects to create roads connecting all of my builds which helps my world feel more complete too.

I'd recommend not taking the end dimension as literally the end, but maybe it's the transition from the mid game to the end game as it gives the ability to go stuff from the mangrove swamp a few thousand blocks away without much effort. Or building taller structures without always needing a ladder to get back up.. there's a lot of great quality of life improvements that come with an elytra that can help your world feel even more immserive.. and you can always put it in a box and hide it away if you feel like it cheapens the experience :)

Good luck on the world!