Well Brightline, or Virgin Trains USA, is more than likely making its way from South Florida to Orlando International Airport. They still have to clear a few hurdles, but the new station at the airport is already under construction and should be completed by 2020.
Additionally, Martin County just reached a settlement agreement that will allow Brightline to roll through there and build another station along the Treasure Coast (includes Martin, St. Lucie and Indian River Counties). Now they just have to settle the lawsuit raised by Indian River County to continue it's trek North. Indian River County actually just rejected Brightline's settlement and even approved more funding to fight it in court. Probably just a waste of time and money but only time will tell.
What happens with Disney and/or Univeral will really make the Orlando to Tampa expansion interesting.