How is it Disney can preserve their classics then ? Here is how. You do not neglect them for years you do preventive maintenance from the beginning. Hopefully they will realize this on newer attractions. Do not let the deterioration get out of control. PM in my opinion is one thing Herschend is terrible at.
Actually if you followed any Disney board you’d see even Disney has trouble properly maintaining their classics and especially their dark rides. Figment is a sore spot for most and the current state of effects in several of the Magic Kingdom dark rides - and don’t forget about Disco Yeti in Everest
World of Motion and Horizons at Epcot; Country Bears, People Mover, Mission to Mars, Flying Saucers at Disneyland; I could go on long lists of rides and attractions that Disney has replaced- and several of those were because they couldn't/ wouldn't maintain them.
But the point is also valid with SDC and other parks- for some reason it seems certain attraction types don't get the TLC and attention that they need- wood coasters and dark rides stand out. Little problems are ignored, and gradually so many little problems add up that it starts to become big problems.
Disney is obviously better than most. But they also are the most well attended and the most expensive parks to visit. When you have more people paying a lot more, then you have more money to be able to spend on upkeep. And they are known for their Fantasyland dark rides- the "classics" But if you've been to a Disney park in the last few years, then it's also likely you've seen their penny pinching and signs of not spending as much to take care of even those as they used to. And Disney far outspends everyone else on taking care of their stuff. And on "atmosphere" characters as well, something that many parks quit doing or cut way back on years ago.
Getting back on topic, I'm hoping to make it out to SDC next week myself to look at the changes. What I've seen it's looking like it's coming along well. I will say SDC does a great job of working on their things and keeping them on a timeline. That's one area they've got Disney beat by a long shot.