-2: we just cancelled the tickets for end of April -- still in the 24-hours "booking period" and we didn't even e-mail back the signed resort form yet. I suspect your only hope at this point is if the airlines get together and impeach the CDC: clearly, the problem is not whether you can or cannot get tested on the island, it's what idiocy they come up with three days before your flight back, and whether you can comply with it then.
PS. it'd be interesting to see how much money the airlines lost in cancellations this week.
Canada has been requiring this for awhile already with some kind of quarantine at home, NYC had some quarantine.
It's just the panic mode that is starting that is BS - IMO, if you want to travel, you felt safe enough to book a trip - this little BS testing requirement shouldn't stop you - Fear Mongering is all it is.
So what happens if you test positive? Probably a good thing to know, go rent a cheap AirBnB and do what anyone else does that gets sick.... If you doubt the result, get another test - order some take out food and relax - hopefully you don't get real sick. The sun comes up, the sun sets.
I'd pure guess, as long as you act responsibly here, the odds of you getting sick are less here than at home during your normal daily life - pure guess but it isn't some raging nightmare here.