If he promises not to play a 40-year-old in the centre of midfield next season, I'd go with a one-year rolling contract, to be reviewed if he gets us promoted at the end of 2021-22.
This season is a write-off and I wouldn't judge him too harshly on our relative underachievement. The first season I do hold him accountable for; last season was a case of starting 6 weeks behind everyone else; this season has been a farce due to COVID. Given the way things are going, I don't think next season is going to be a time for radical change.
I don't think anyone would blame the owners if they decide to look for someone new, but how about for once we take a gamble and stick with the manager to see if he can get his project over the line?