When hotels change brands, it often happens suddenly. Paid reservations are generally honored. Award reservations are sometimes honored. In either case, though, elite members of a loyalty program should not expect new management from a new brand to honor the benefits guests were entitled to in that other program.
Sometimes hotel chains do a good job re-accommodating guests with points bookings that are displaced. Sometimes they don’t do a very good job. However even when they do it can be stressful for the guest. And for employees.