They need to remember that they couldn't have had Tatum. Danny had the #1 pick, and agreed to do the trade because he didn't want Fultz. If Philly had said they were going to draft Tatum, Danny would have just taken him with the #1. They could have had Ball (and his dad) instead, or one of the other top 10 choices. It may take a couple of years to see how this plays out, but it sure looks like Philly messed up. The chance of Fultz being as good as both one of the other top 10 picks in this draft, plus a top 10 pick from the 2019 draft (Kings pick) is pretty darn low.
Do we think the trade is made with a promise of who they would take? If they said we are still deciding, would ainge refuse the deal?
No way to know for sure, but it seems that way. If I was making that deal, I would ask them who they were planning to take. Sure, they could lie about it, but if they did, word would get out that they had a gentlemen's agreement and one team reneged on it, and no one would want to deal with that team/GM again.
In some cases, the trade is actually made as soon as the picks are made, though I don't think that happened this time - since we had the #1 pick, there was no risk of another team screwing up the deal, as LA had made it obvious they were drafting Ball in the #2 spot. In those cases, the GMs get together and say 'I want Fultz' and 'I want Tatum', and once the picks are made, the trades happen. I think Danny did this when we got Kelly O, though I can't remember offhand who we drafted.