Assuming this is true, now seems like a very good time to sell. Valuations are being driven up by the competition between Vail and Alterra, and the economy is still doing quite well. I would have to imagine that Jackson Hole would fetch a mighty price. It's exactly the kind of "iconic" destination resort that Alterra wants in their portfolio.
Most of the resorts on the Ikon Pass that hardcore skiers salivate over, resorts like Alta, Snowbird, Jackson Hole, Revelstoke, and Aspen, are not actually owned by Alterra, they're just partners. Squaw/Alpine, Mammoth, and Steamboat are the big-name resorts owned by Alterra. Partnerships help grow the Ikon Pass, but I have to imagine that the Ikon Pass is really just a means to an end in Alterra's long-term plan. They're ultimately interested in driving people to properties that they own so that they can capture more of the value that customers bring than just the lift tickets. They also want food, retail, lessons, real estate, etc.
One more thing to add: would Jackson Hole go unlimited on the Ikon Pass if it's bought by Alterra? I'm not sure. Squaw/Alpine and Mammoth are unlimited, Deer Valley is not. I heard a rumor that the Crown family (owners of ASC) may have bought Jackson Hole, not Alterra, in which case it would certainly not become unlimited.