I suspect that the big winners in the situation are going to be lawyers. As Kmnmiamisax says, if Maryland exercises a right to eminent domain, they have to have a place to run the race. Where are they going to do that? There's Timonium Racetrack, which hosts a few days of racing in conjunction with the fair they have there. Hardly a place that could handle the quality of horses and the size of crowd that the Preakness draws. Ocean Downs? That's a harness track, it would need major re-working to have Thoroughbreds race over the surface, and it's not built for a crowd the size the Preakness draws. Rosecroft Raceway? That's another harness track. Same problems as Ocean Downs.
Fair Hill Training Center has a 7/8 mile Tapeta-surfaced track, and they have a one-day meet with steeplechasing, hosting about 15,000 spectators. The track is too small for the Preakness and the facility would be overwhelmed by the crowds.
If MEC sells Pimlico and Laurel for development, I suspect that what would eventually happen would be that the rights to the Preakness name and conditions would be sold or leased to another track on the eastern seaboard. I don't think this is necessarily a bad thing and it may be the only way to ensure continuity for the Preakness.
Myself, I think that if Pimlico goes under the developer's bulldozers, it may be time to "stick a knife" in the Preakness and let it go, and offer the Travers Stakes at Saratoga as the third race for a new (and better) Triple Crown.
I know the mere thought of that will raise a storm of outrage, but I think it makes sense. The Travers has a long and storied history and tradition, and many champions have raced in the Travers Stakes. It's at the classic distance of 1-1/4 miles, which is actually a better distance than the 1-3/16 miles of the Preakness, which has always been an oddball distance. The spacing of the Derby, the Bemont and the Travers is much better for the health and safety of the horses that contest the Triple Crown, because there is more time between races to recover. And if you want to talk tradition, the English Triple Crown consists of the Guineas Stakes in May, the Derby Stakes in June, and the St. Leger Stakes in September. Why shouldn't the American Triple Crown have about the same spacing?
Times change, things change, and if the Preakness can't be run under first-class conditions with assured continuity, I say let it end gracefully and start a new tradition: The Triple Crown of Derby, Belmont and Travers stakes.