I think they are definitely a good team, albeit with some serious injury concerns. Warren missed all last year. Harris missed almost all of last year. Who knows what's up with Simmons' back. Durant had a knee issue for a couple of months and obviously has a significant injury history. Kyrie's health record is pretty spotty, having played more than 75% of games in a season 4 out of 11 years in his career. Injuries can obviously happen to any team, but their top 6 (starters plus Warren) missed an average of 55 games last year. Yes, Irving and Simmons were to varying degree self-inflicted, but it's also unlikely either were going to play the entire season even if they didn't have their separate issues.
I also don't think there's a prayer they can patch things up with Kyrie, and thus, by extension, Durant, so in my opinion it's pretty moot.