This is a weak free agency whereas 2021 will be loaded, so it definitely makes sense for Hayward to opt out so he can secure a big, long contract with greater security, even if it means earning far fewer dollars in 2020-2021. As such, I predict he will opt out. If he does, what kind of odds would you put on us getting him for $125 million over 5 years with a player option on the 5th year?
Besides 2020 free agency being weak and 2021 being loaded, I disagree with just about everything else here.
It would be better for Hayward to opt in, because it's a weak free agent class this year and strong next year.
2020, only a few teams will have cap room. None of them are desirable as far as I know. A 30 year old All-Star caliber player isn't going to want to uproot his family and play for a rebuilding team like the Hawks.
In 2021, when more teams will have cap room, there could be a lot of good situations for Hayward to go to. Think of it like if you were a free agent this past summer. You could have signed with IND, UTA, LAC, MIA, BRK, BOS, PHI, GS etc. You could team choose to join an existing contender or team up with other superstars and make your own. That's what 2021 might be like.
As much as we love Kemba now, he was probably plan C or D for the Celtics. (Plan A being trade for AD, Plan B being re-sign Al and Kyrie, etc.).
Horford was probably plan C or D for Philly, (Plan A and B was probably sign Kawhi or Durant, Plan C might have been to bring back Butler, etc.)
I doubt D'Angelo Russell was Plan A for the Warriors.
Danny Green was probably Plan M for the Lakers.
Julius Randle was probably Plan Z for the Knicks...
This is why you want to be a free agent when a lot of teams have money. You can get your money and go to a good situation.
Opting out if his goal is to re-sign a long term deal in Boston makes sense. But opting out thinking there will be a huge market of desirable locations that will bid up your price doesn't.