We've got Timewalking; scales players down to the level of content and scales the rewards up to a point where they're useful. Brilliant, fantastic, but why stop there? It's not available all the time, and there's more you can do with the system.
And in Legion, there's Challenge dungeons or Mythic Plus or whatever it's being called this week. This sounds good, this sounds very good; the content theoretically scales until it snaps you like a twig for daring to look at it sideways. But again, there's more you can do with the system.
Even the world content scales in Legion, and that's the key to success here.
The most successful content in WoW? Battlegrounds. These things have paid for their own development and art time and resources God only knows how many times over. That's the sort of thing we need for raids, which get no-lifed into the ground until the next one comes out and then gets virtually forgotten.
So let's fix this, let's get all raids and dungeons in the game lasting forever. Remove Timewalking for a start, and bake the functionality into all raids and dungeons. You go anywhere, it scales to your level and so do the rewards.
And every time you beat it, it gets a little tougher--but the rewards get a little better too.
By all means, find the one sweet spot halfway through the levelling range where the bosses blow up in seconds; it won't do you much good, because the rewards will be low-level variants and worthless once you get a few more levels under your belt.
No timers, though. This is a test of skill, co-ordination and teamwork, not a sprint to the finish.
Regardless, that's how you make content last forever. Ulduar? Current content. Sunken Temple? Current content. Grim Batol? Much as I wish otherwise, current content.
Now we've got content that scales infinitely, we don't need multiple levels of difficulty. Heroic? Mythic? You'll end up there in the end if you're good enough, no need to have countless UI buttons to click. Raid size? Doesn't matter; we've got flex. Make it all flex if it's not already.
Raid Finder? Let's fix it.
Broken Shore spawns in NPCs from what I hear if there aren't enough players. Use that, like the event at the end of Hyjal with Cenarius or the legendary quest with Khadgar and Chromie.
Call it Story Mode. Use it to keep people like me out of the raiders' way. Don't hold bosses back from us, though. Sinestra? Ra-den? I want to fight them. Who the hell is Ra-den? I want to know. I want to punch his smug face in.
So anyway.
Story Mode. Challenge Mode.
Nothing expires, everything scales.
Everything lasts forever.
Everything is current content.
Boom.
Content drought? Fixed.
Next expansion? Flatten the iLevels, reset Challenge Mode, start all over again with more dungeons and raids added to the mix.
Bring back Scenarios. Make them scale too.
Done.
Cut me a cheque.