Kyle and Belinda Have Been Living in Their Home for 25

Kyle and Belinda have been living in their home for 25 years. For the duration of their time in that house, they have used a small cement walkway that passes through a large field to walk to the nearby beach. Gary owns the large field and paved the cement walkway, himself. Last year, Gary decided to build two condominiums on the field, with the walkway dividing them. After noticing Kyle and Belinda using the walkway, he yelled at them and told them that they can never use his walkway again. Gary promptly erected a large gate to prevent Kyle and Belinda from using the walkway. Because the condominiums are so large, there is no other way for Kyle and Belinda to get to the beach. What may allow Kyle and Belinda to continue using the walkway? Fully explain your answer.