If we count recent openings, here is a list of new golf courses in various stages of development in Palm Beach, Martin and St. Lucie counties
Apogee #1 (Hanse)
Apogee #2 (Fazio/Davis)
Apogee #3 (Phillips)
Astor Creek (Wilczynski)
Atlantic Fields (Fazio)
*McArthur - West (C&C)
Panther National (Nicklaus)
Sandhill Crane - The Nest (Nicklaus)
*The Park West Palm (Hanse)
The Ranch 1 (WAC)
The Ranch 2 (WAC)
Wylder (Furyk)
I'm aware of at least one more, which would make at least 13 brand-new/in-construction/planned golf courses in those three counties at the moment.