I'm not so sure. Although it is the largest, I believe that is mainly because almost half of the pavilion is a greenhouse. Not really a guest area at that. However, that is the only counter service food location on that side of the park.
I believe that the park can do without Living with the Land and Circle of Life for a while. However, I'm not so sure about the Sunshine Season Food Fair and the Garden Grille. This severely limits your eating choices in Future World. In all of Future World, there will be only one counter service eatery, one table service eatery, and an expresso bar. Then of course you have the outdoor carts everywhere, but still. I believe this creates a major problem. Not really attraction wise, but food wise in Future World. Are there any plans to re-open the Pasta Piazza Ristorante in Innoventions West while this rehab is going on?
I know you find it odd that I'm not concerned with attraction choices, but I think the FOOD will be the main problem. Future World's attractions are still there, and if Future World didn't have World Showcase to compliment it, then you'd have a problem. But since it does, there's plenty of things to do to fill a day at the park.