There is no way the park would have been able to stay open for too long
Hammonds design was very much not sustainable, I mean how many tours was he going to be able to have going on at one time? Maybe 10 or 11? That means the number of people he could have in the park at one time is minimal at best. The wait list to get into the park would have been ridiculously long, the people going to the park would have to spend a whole lot of money getting there considering they'd probably have to get plane tickets to Costa Rica first and then take a boat to the Island and then once they get there they would have to wait an incredible amount of time for their tour to start considering once again with the cars only so many people can be viewing the dinosaurs at one time. Not to mention the staff would have to completely focus on each tour group to make sure they were safe (having them that close to the dinosaurs was a huge safety risk) and to tempt the dinosaurs with goats if needed.
Hammond should have designed the park so that people can walk around at will and go see whatever dinosaur they wanted and of course have the dinosaurs a much further distance from the tourists (perhaps have the walkways on top of a cliff and the dinosaurs are in a cleared out field at the bottom of the cliff?)
Either way with that design there was no way he was going to be able to generate the revenue to keep the park open for too long. I'm guessing they were also going to have to build hotels on the Island as well, no way anyone would be able to A) Fly to Costa Rica, B) Take a boat to the Island, C) Have a fun exciting day at Jurassic Park, D) Go home, all in one day.