I would like a few more details rather than Tatum and Brown not making the All-Star team. If both have stagnated and aren't proving much in the way of future stardom, then sure, I would make the trade. KAT would be under contract for several more years and would be a clear upgrade over those two (again, assuming both have stagnated). It would be more important to lock down one young perennial All-Star over two players who aren't showing that potential, regardless of the ages of the rest of the players.
I don't anticipate this curve for both Tatum and Brown, just showing a scenario where I would trade them both. If they both come out and are awesome this year, but just don't make the AS team, then no, I don't trade both of them in a deal.