If every old ride there had to remain forever, because... Heritage... They wouldn't last the next 20 years as they'd never be able to add anything new.
Protect Ghost Train, Flying Machines, Dipper and Nash... They can bulldoze the rest for me, as long it means they can keep moving forward for years to come.
Edited to add: I fear the protected status of some of their rides will be a nightmare for them in the future too. Whoever applied for them to be listed wanted to protect them, obviously, they acted in good faith with admirable motives. But what if the park becomes nonviable because they're straddled with the expensive upkeep of rides that nobody even wants to ride anymore? What if those rides mean fewer and fewer additions, and the park falling further and further behind the competition, because they haven't got the money or space for new rides, due to the listed status of old ones. We'll lose the park and the rides...
Don't get me wrong, I love the Nash, it holds a very special place in my heart, was my first woodie, and I absolutely loved it back in the 90s. But if I had to choose between losing the Nash now, or losing the park in 20 years, that choice is fairly easy.