If Keller needs TJS, he's very likely out for all of 2027 as well making 2028 a rehab season pitching in AAA for someone. Perhaps in 2029, he'll be someone's bounceback. Again Robertson is a good reference--pulled up lame in 2019, TJS that summer, missed 2020, pitched for the Rays AAA affiliate in 2021 before making it to Tampa late in the season and then being good for the Cubs and Phillies in 2022.
Maybe Robertson will come out of retirement again for us? 