Systems have one legitimate use: Prevents button bloat. If those powers were introduced as permanent features of the class, every 2-3 xpacs the DPS rotations especially would be borderline unmanageable.
Having said that, keep the “xpac power” feature if you must but get rid of the rest of the crap. We’re getting so many different currencies right now, I don’t know what they do. I 'm not fully aware of how Shards of Domination are supposed to function and I’m sure I’ll mess it up when I start working with them (which is apparently going to be awhile, as my main has yet to receive a piece of gear with a socket of any kind on it).
As to what I expect, the Dragon Isles xpac has been talked about and rumored so long it sort of feels like how we felt a year or two before Shadowlands got officially announced. But as cool as Dragon Isles could be, it’s not going to save the game unless Blizzard takes some successful, big swings at some of the things that are broken. They can’t just chip around the edges.
Mostly, going into the next xpac, whether people like it or not, they need a new class and race both. You can argue balance issues until you’re blue in the face, but the truth is those things get people talking and planning. Dragon Isles leads you into Dragonsworn and other possibilities.