Different. This is an evolving environment, and has always been. How it is when we are alive is not how it was before us, and will not be how it is after us. Change is its natural state. The human effect on climate is one aspect of change. Yellowstone is our test case. Our control, in a scientific experiment. Our landscape and environment will be changing significantly over the next 100 years. There is no getting out of that. Those changes will be accelerated and amplified by human activity. But having a space like Yellowstone will allow us to map that change clearly and scientifically. Yes, it will be different. But it always has been. (Not excusing our role in the change of our climate. Just stating a fact.) It's easy to see things as "set in stone" when their change happens slowly over decades, and then to deplore the changes as "not the way it was". But what says that your lifetime has any relevance to a mountain?