Okay, I won't actually be seeing The Rise of Skywalker until tomorrow night, so I can't claim anything with regards to its quality or what it does or doesn't retcon from The Last Jedi. However...
This is the part of your post I was actually addressing. Going by the inflation-adjusted box-office numbers, each entry in the three Star Wars trilogies ranks thusly in the list of all-time most successful movies:
Original Trilogy: 2nd, 13th, 17th
Prequel Trilogy: 19th, 99th, 70th (with the Clone Wars movie being splattered on the windshield of The Dark Knight)
Sequel Trilogy: 11th, 44th, probably somewhere between 30th and 50th (with Rogue One being 62nd, and Solo getting trampled underfoot by Infinity War and Deadpool 2)
Hmm... looks to me from that list that one could actually argue that it was the supposed God-Emperor of all that is Star Wars, George Lucas who oversaw the financial decline of the franchise, and that Disney helped it rebound slightly (albeit their financial mismanagement of Solo went WAY beyond anything that happened under Lucas's tenure).
Domestic only, though, which makes the original trilogy uniquely strong in this comparison since it grossed 50% - 60% there. But even adjusting for inflation makes up for a poor metric since that takes into account average ticket price, but blockbusters nowadays are so much more oriented toward full price weekends, premium screenings, 3D etc. than the average.
Either way, I think the point I made on the other thread stands - the franchise is demographically stagnant for decades and thus increasingly less relevant to pop culture worldwide as population grows and the middle-class expands on Asia and elsewhere (that's not to say, of course, interesting things like fads or popular memes can't happen with Star Wars in the future even if it continues down this path).