There are currently 63 National Parks in the United States: https://en.wikipedia.org/wiki/List_of_national_parks_of_the_United_States

Will any of this set be sold off, downranked as National Forests, National Monuments, etc., or otherwise lose their designation?

This does not count losing land area or other changes to the Parks as long as they maintain their National Park status.

Any such action will count for resolution until the term is over, i.e. until inauguration in January 2029. This action must hold until that date. If such an action has been taken but is held up in courts and may be reversed, I will poll Manifold on how likely the action is to be upheld and resolve to that percentage.