I believe that there are other survivors of Ohara. I think that a people as intelligent as the ones from Ohara would not be so naive as to put all of their poneglyph readers in one place. Studying poneglyphs is illegal and extremely dangerous. They were aware of this. I think that there are other poneglyph readers in hiding from the WG after the Buster Call on Ohara. No one is attempting to make contact with Robin currently because she is too high profile. However, after Luffy becomes pirate king, he will set up a territory where all survivors of Ohara can come and live peacefully under his protection. I don't imagine that there would be more than 5 or at most 10, but they would be able to come together for the first time in over 2 decades and remember Ohara together.
I believe that without other survivors of Ohara to unite with at the end of the story, Robin is essentially marked for death. Her "I want to live" speach in Enies Lobby is a death flag. However, I want Robin not to be marked for death. With nothing except the Straw Hats to be there after she fulfills her dream, she would be lost. There would be no real future beyond her goal of finding the answers to the void century. Rayleigh already noted that the answers are found on Laugh Tale. Once they reach Laugh Tale, it is the end of Robin's adventure. She will die in whatever battle will follow (likely Luffy's attempt to bring down the WG). Unless there is something that can provide her with a new dream, she will be likely killed off.