1. No one knows for sure, but I'd say it's highly unlikely that it would close again as long as the parks are open. It is possible, though, that, if they need more capacity than the Swan has, but not enough to have both the Swan and Dolphin open, they might move everyone to the Dolphin. But again, that's just speculation.
2. While the Swan was commissioned by Disney, and Disney owns the land, Disney does not actually own or manage the Swan or Dolphin, so you would not get moved to a Disney-owned resort. Marriott currently manages the Swan / Dolphin, so in the unlikely event that both the Swan and Dolphin close, you'd probably get moved to another Marriott resort.