It can be a planned expansion, a 15 year master plan add on, or a complete pipe dream. Doesn't matter.
There's lots of good terrain right next door to many resorts. Pick out land you'd like to see added within the skiable boundaries and state your case!
Sugarbush VT- Slide Brook area. When I lived on the East, the 'Bush was my favorite mountain. Just a really diverse place with a lot of wild terrain. The Castle Rock pod is an absolute riot. The amount of terrain between Ellen and Lincoln is about 2000 acres. They do guided tours back there now and much of it a black bear habitat. I'm sure they could find a few hundred acres that be acceptable. Throw a double back there and you'd have some steep tight trees runs loaded full of snow.
Pico VT- Connection to Killington. There's already a cat track there. Wouldn't take much and you'd finally connect two mountains already on the same lift ticket.
Vail CO- East Vail expansion. Vail has pretty much you'd ever want in a ski area except for primo expert terrain. East Vail changes that. Gnarly, technical, cliff bands, steep and a boatload of fun. Throw a lift over at the base of the Mongolia bowls that gets you to the top of the ridge. No lift ride out of E Vail. You wanna get back to the mountain? Take a bus from I70 back to Vail Village. It's a very dangerous area that has taken a few lives. If VR wanted to pitch the expansion as a great way to minimize the danger through avalanche mitigation, they might be able to pull it off. Plus, they could push 6000 acres with something like this.
Winter Park CO- North Cirque expansion. Get a lift that heads WSW from the base of Eagle Wind and accesses the ridge from the Waterfall area north toward Vasque ridge. Its more sheltered than the Cirque so you wouldn't anywhere near the avalanche or wind closures that they currently deal with.