Who should pay for this?
I know you are not asking me, but from a logical point of view the landowner could/should try to change it. The landowner would have to become Orlando, no private landowner would be naive enough to allow it under their name, meaning Orlando or any group foolish enough, would have to purchase the land.
However, it is a swamp. That means a lot of plumbing would have to go in to divert the water, add solid foundation and soil, a lot of clean up, (more things I am not aware of as I do not do City Public Works) a lot of "constant and consistent" care if it is to be "public land" not "private land". Someone has to pay a load upfront and a load forever.
If it became "public land", which is the only way the landowner would do this is if Orlando bought it, (no land owner can take on the responsibility for safety and upkeep of public land), that equals Florida Tax Payers, for as long as it is "public land" which would equate to forever most likely.
That means constant checks and repairs on the elaborate water diversion, constant cleaning, mowing, police patrol, lighting, fencing, animal control for the critters and snakes, sidewalks cleared and usable, and more.
"Public land" equals Florida Tax Payers.