I'm sure we can entrust our theme park operators to do the bare minimum window dressing possible to satisfy everyone they're doing all they can while doing the least possible cost-wise.
I suspect they'll keep park capacity the same, put up some signs in the queues telling people to stay separated, but not actually police it unless one guest thumps another guest for getting too close.
They 100% will not clean trains after every ride - its just far too labour intensive, and slow. you might as well not operate the ride.
Honestly with WnW - (and i love that you're talking about parks in general but completely ignored White Water World), I think i'd prefer to go to WnW than MW when things to reopen - there's a lot more chlorine there to kill bugs. Just up the concentration a little and you probably don't even need to ask people to wash their hands - just keep them underwater until they've finished singing happy birthday...
I saw around the traps today images of a park in China that had reopened, and locked out every other seat on its roller coaster for 'distancing'. I don't see MW going to that extent, but if they did, i'm sure they'd still find a way to argue that the rear seat on DCR was exempt because people facing backwards couldn't spread droplets forwards or something.