Before I say this, I appreciate the situation with your new owner and stadium, and your proud history. And I'm going to speak in a long post about my team, which I hope isn't too annoying for everyone.
But speaking from my own experience as a Sunderland fan, I'm an advocate for relegation being a tough medicine but also still helpful in the long run. I think it's really the only way to properly sort yourselves out, and you'll come back stronger.
Having said that I'm a fan who goes home and away, and quite frankly I only care about watching Sunderland. So the opposition doesn't matter so much anyway, be it Chelsea or Cheltenham. So I come with biases etc. if you live abroad and really like PL football, obviously you'll think differently.
But since being relegated we've been able to drop our wage bill completely, shift off the dead wood, implement long term changes to our recruitment and analysis (impossible to do in the PL where everything is short term) and bring through a host of home grown talent from the academy. As it stands we have the youngest squad in the football league, and plenty of talent that will go on to play top level football in the future. We've also won a minor trophy (behind closed doors because of Covid), been to wembley four times, a had a special day in which we won at Wembley for the first time since 1973 in front of 60k of our own fans. Ask a Sunderland fan there and it'll of been one of the best days of their lives, even if it was League One playoffs.
The upshot as a fan is you actually see your team win games, absolutely loads of them to be honest. And even when you do lose, you don't expect to lose every week. The psyche of the supporters base (and the city) has changed as a result. You can be optimistic and happy, and there's so much pride and good will. The games are class too, it's normally end to end exciting football - no drab sitting 11 behind the ball hoping for a 0-0 at the Emirates or whatever (been there, done that!)
The away atmosphere is class these days, and everyone is desperate for tickets. There's new songs about players and people are enjoying it. There were times going away was a slog, now it feels like a proper day out.
It's taken some years of misery, but we have sorted out our club and I think our fans are as happy as they have been since the 2001 era. I just don't forsee a way we could of ever had the same fun, memories or pride without going down and rebuilding.