My understanding is that the USGA had to move heaven and earth to convince the powers that be at Shinnecock to let them come back; I wouldn't be surprised if the Open was never played there again.
Well then they would have to change their plan, for the USGA has already announced that they are hosting the 2026.
2019: Pebble Beach Golf Links - Pebble Beach, Calif. - June 13-16
2020: Winged Foot Golf Club (West Course) - Mamaroneck, N.Y. - June 18-21
2021: Torrey Pines Golf Course (South Course) - San Diego, Calif. - June 17-20
2022: The Country Club - The Country Club - Brookline, Mass. - June 16-19
2023: The Los Angeles Country Club (North Course) - Los Angeles, Calif. - June 15-18
2024: Pinehurst Resort & Country Club (Course No. 2) - Village of Pinehurst, N.C. - June 13-16
2025: Oakmont Country Club - Oakmont, Pa. - June 12-15
2026: Shinnecock Hills Golf Club - Southampton, N.Y. - June 18-21 2027: Pebble Beach Golf Links - Pebble Beach, Calif. - June 17-20