I'm going to take an early guess and say we trade Ayton to Atlanta for John Collins and the #16 pick. Likely some salary swap too.
That wouldn't work. Collins makes too much. The most the Suns could take back in a sign and trade for Ayton is around $19 million. Collins makes like $23 million. Players going out in sign and trade deals can't be combined with other outgoing players.
The #16 pick and Capela would work and make more sense because they couldn't play Ayton and Capela together. Plus Capela is under contract for 4 more seasons. There's no way they'd pay a backup that much.
Capella and #16 is probably as good as we'd get in return.