A cheap peso is great for tourism and exports but bad for gas and other imports.
President Medina has already signaled that he will help boost exports. To that end he must keep the peso weak. And, as you correctly point out, the other beneficiary of a weak peso is tourism/tourists which by banco central figures is growing stronger/climbing.
And as been pointed out above, the losers in this appear to be the citizens/residents who are paid in pesos. The interesting point here is that there is a growing consensus for higher wages from any number of emplyment sectors. Education is demanding a pay increase, transport is demanding further subsidies, and so on. This would be an inflationary event and cause still further weakening in the peso.
The net effect is a peso that looks to continue to weaken vis a vis the Dollar/Euro. The only question is how rapidly?
And that answer depends largely on many other factors outside of the DR. If the Federal Reserve decides to switch from a weak dollar to a strong dollar policy, that would of course be very bad for the peso. If Chavez dies, and he is not well at all, then the Petrocaribe agreement would be in danger and that would have a massive and immediate effect on the economy of the DR and by extension the peso. These are by no means the only factors, but they are the ones the DR should be most concernned with at this point.
To the OP's question, while I can not and will not predict when the peso will hit 50:1, it will certainly be before it strengthens to 28:1.
Respectfully,
Playacaribe2