I can agree that we need some changes to the formula and that it can be done without fundamentally changing the game's formula so much as iterating on it.
For starters, leave the tomestone cap at 900. By having that cap much higher it encourages people to play more and do more content to reach their weekly cap which helps queue times and keeps people engaged.
Secondly, I like the Ex roulette concept, I really do, but I would want to see changes to that as well. Specifically, give us more than just the two dungeons to run. If they really can't come up with more than two dungeons, then combine the Ex roulette with the inevitable 70 roulette and up the rewards so it's equally as rewarding regardless of the dungeon you get and to prevent the issue of overgeared players blasting through it too easily, apply an item level cap. So then as the expansion continues, the highest level roulette will have several different possibilities there instead of just two.
Next thought is the acquisition of your tomestone main hand weapon and the 8man raid progression in general. I'm not a fan of the "seven weeks running the last 8 man to get it" system and I'd rather detach the tomestone gear from the raid. I would prefer making the 8man non-savage mode it's own form of progression. To elaborate further, I fully agree with Savage mode having the highest ilevel stuff, that's perfectly acceptable, what I'm suggesting is making the normal mode 8man gear equivalent to the tomestone gear and having a full set of gear (including weapons) be acquired from there so if I want to skip tomestones and farm a set of gear from there, I believe in giving players the option to do so.
I also am all for giving players a variety of options to do the upgrade system for their tomestone weapon/gear. But with what I outlined above rather than just have the upgrade be from the 24man, why not also add variety on where to get it from? Let us buy it with tomestones, hunt marks, get it from the 24m, and get it from the savage mode while applying whatever weekly cap to get it? On that note...
Make the 24m it's own form of progression as well and with the upgrade item I mentioned, give us the option to upgrade the tomestone gear or the Alex gear or the 24m gear and let us gear up that way rather than the tomestone gear being the only set we can upgrade.
There, I've suggested a variety of ways to let us experience the end game content while keeping the formula intact and iterating on it.
Edit:
We can probably keep EX mode primals where they are, between tomestone weapons and savage. I think that's fine as is tbh.