Pulled together a list of all acts who were on this year's poster who have been announced for other festivals next year or have rescheduled tour dates around Glastonbury:
Diana Ross, The Specials
AJ Tracey, Blossoms, Declan McKenna, Fatboy Slim, The Lightning Seeds, Mabel, Metronomy, Nadine Shah, Pet Shop Boys, Sam Fender, Skunk Anansie, Supergrass
Brittany Howard, Greentea Peng, Isley Brothers, Kano, Kelis, KOKOKO!, Nubya Garcia, Thom Yorke Tomorrow’s Modern Boxes, Tom Misch & Yussef Dayes, TLC
Beabadoobee, The Big Moon, Burna Boy, Charli XCX, Editors, FKA twigs, Glass Animals, Jehnny Beth, The Jesus and Mary Chain, Primal Scream, Tones and I
Baxter Dury, Big Thief, Caribou, Fontaines D.C., Goldfrapp, Khruangbin, Manic Street Preachers, The Orielles, Sampa the Great, Squid, Tinariwen
Candi Staton, Crowded House, Elbow, Groove Armada, Herbie Hancock, Imelda May, Rufus Wainwright, Sinead O’Connor, Suzanne Vega, The Waterboys
I've probably missed some acts and there's also acts like Dua Lipa, Anna Calvi and Happy Mondays who have dates for early 2021 but nothing for the summer yet.