My speculation on potential winners returning:
Martin Stenmark - Possible (but he's done so much since his ESC flop that he's not remembered as a Mello winner in Sweden)
Carola - Generally unlikely
The Ark: Minimal chances
Perelli: Unlikely in 2024
Ernman: Generally unlikely
Bergendahl: Unlikely in 2024
Saade: Unlikely in 2024
Stjernberg: Possible
Sanna: Won't happen in 2024
Måns: Publicly stated he won't return the year after a win, has indicated he's very interested in returning around 2026
Robin B: Pretty likely
Benjamin: Generally unlikely
Lundvik: Possible
The Mamas: Not likely as The Mamas in 2024 (SVT preferred LouLou for 2023), Ash or Dinah returning is entirely possible
Tusse: Pretty likely
Cornelia: Unlikely in 2024
Loreen: Won't happen for the next 4 years