My $0.02: I think they should reintroduce relegation from the Premiership for the coming season, and promotion from the Championship the season after that.
Reduce the Premiership to 12 clubs ASAP, and buy some time in which to figure out the practical aspects of promotion (unless the first club to qualify for it in 2023-24 is the same one that goes down in 2022-23, in which case the whole 'Is your ground big enough?' nonsense shouldn't come into play at all).
Going up to 14 clubs in the Premiership sounds like an exercise in greed and hypocrisy, especially as the powers that be keep touting their alleged concern for player welfare - more games in a season may be good for the clubs' coffers, but not for the players who have to spend additional time on the pitch.
Lastly, I'd like to see the draconian ground requirements waived (for a while, at least) in order to give more clubs a realistic shot at top-flight rugby. Don't make Ealing threaten to sue for a place in the Premiership, when they earned it throughout the season; don't encourage Pirates to go the same way as London Welsh, by asking them to grow beyond their means.