That won’t happen it would mean the Championship operating two teams short.
From our point of view the biggest thing in our favour is Liverpool, should footie be unable to continue after April 3rd whatever decision is taken regarding how the winners of the Premiership is decided that would cascade down the pyramid. At the moment I’m comfortable with our position.
I think the no relegation option could happen if things can’t continue after April the 3rd.
IF the PL didn't have any relegated teams but they did allow promotion for a year due to teams like Leeds/WBA etc fighting them in court and expand the league, as you say it would leave Championship two short, so if anything what you'd do is increase the number of promoted teams from each league below by two (prob three from L2 to cover Bury) to maintain the numbers.
Clubs aren't going to complain not getting relegated, the teams in the promotion spots still go up and a team or two in the play-offs gets the added bonus of a promotion they weren't expecting.
There is still an issue of teams below that in the play-offs or just outside, but IMO it's fairer than just voiding a season 75% in. Had it happened around Nov then sure, but not now.
Don't think this will happen though and I still prefer the idea of just continuing when possible and any changes occurring for next season, such as cancelled cup competitions to allow more league games, or cancelling next season if it goes on well into summer.