Here are some things I came up with to make Knott's the "perfect" park.
-Take out Boomerang. The ride is as old as dirt and isn't enjoyable to ride anymore.
-Give Ghostrider some new trains. Millennium Flyers or Timberliners would be nice.
-Take out a flat ride or two in Fiesta Village. It seems a little "crammed" in that area of the park. Maybe the Hat Dance and/or the Dragon Swing. This also opens up this edge of the park for something special...(wink, wink).
As for the old PP spot, it could be anything from a B&M hyper coaster with a splashdown to a Mack splash battle. All we can do is wait and see.
Some of these idea are a little hypathetical but I think it might make the park look a little more nice.