I'd contest this a bit. Yes, it's one of two major chain parks in Canada, and of the two, I'm under the impression that Wonderland is considerably better. However, I think Cedar Fair recognizes that people have options for entertainment, and roller coasters don't have to be part of it. If I remember correctly, that was mentioned several times during the Ouimet years. I don't remember if this was explicitly said or if it was just implied, but the sentiment was, "We're not competing against other parks, we're competing against other things people do for fun." I could be misremembering this, but I feel like that idea was mentioned a lot in reference to Cedar Fair exploring other entertainment options (like cirque shows) and the (former?) Amusement Dark initiative.
I'd also add that I think considering parks too big/centrally located to fail is a dangerous fallacy for any park owner to believe. I'd argue that that kind of thinking is part of what enabled Six Flags to do what it did to Geauga Lake in the late 1990's and early 2000's. I think it's also part of what contributed to Hard Rock Park's failure, and I think it's part of the path that Mt. Olympus in Wisconsin Dells and Buffalo Bill's in Las Vegas have been heading down for some years now. Consider Dollywood as a counterexample: it COULD be just another shticky sideshow attraction like everything else in Pigeon Forge and coast by, but it's lovingly cared for and expanded by park management, even though gazillions of people travel through the area year after year. It's got longevity because of that care.