Not a perfect trade by any means, but hear me out.
While in theory the smaller, switch-everything lineup of Kyrie, Brown, Hayward, Tatum, and Horford should work, I'm just not sure it translates to practice right now for a number of reasons - lack of definition of roles, too small upfront, Hayward's recovery, having younger guys in the mix not buying into lesser roles, etc. And while a similar system has worked at GS, they were all at much different points in their careers, which I think is a major factor of why it worked.
And I actually like Brown at the 2 much more than Tatum or Hayward, but I think trading Tatum or Hayward is not ideal at the moment - Tatum being too valuable with a higher overall ceiling and Hayward not fetching an ideal return right now when he's not fully back recovered, let alone the optics of trading him after last year's injury.
However, what this would do is better define our starting five's roles and give us a more appropriate power forward who is also versatile as a defender. Kyrie, Hayward (once fully recovered), and Tatum would then have more overall touches in the offense and could better serve as our offense's "Big 3" like they are designed to be, i.e. better fit in their roles.
Carter Jr. would also be a long-time starter for us with All-Star potential. And while I do think it's clear that his ceiling is lower than Brown's ceiling, he much better fits our team's needs right now (and probably in the future), and at this point with as much wing talent as we have on our roster, I don't think Brown could effectively reach his ceiling with us anyways. I also suspect he's not happy in his current role and thinks (likely appropriately) that his game is being held back offensively by such a role. I don't think you have that problem with a player like Carter Jr.
Carter Jr. would also have the added bonus of being a perfect Al replacement with the appropriate timeline, also giving us two more years on a rookie-scale contract to punt some of our financial issues down the road a year or two.
If we think we could play with Hayward/Tatum at the 2/3 (which I'm still not 100% sold on), then I think that lineup of Kyrie, Hayward, Tatum, Carter Jr., and Al fits really nicely together both now and in the future. It lets Kyrie, Hayward (once recovered), and Tatum take a more prominent role in the offense like their talent suggests they need, while having Horford and Carter Jr. there as defensive-minded but still competent offensive players capable of knocking down the open shot and finishing at the basket.
Not sure what else would need to be added to this deal to make it attractive enough for both sides, but I like it for both sides, as I could see Brown really excelling in Hoiberg's fast offense alongside Lavine and Parker.
What do you think? Is this a fair trade that would benefit both sides? I'd hate to lose Brown - who I do really like at the 2 long-term even if he's stunk it up this year - but I'm just not sure if we can really play all three of Brown, Hayward, and Tatum at the same time. And of all of them I think Brown makes the most sense as a trade candidate right now given the context of the team and other players.