Kyrie leaving is fine. Losing Horford is really bad in the short term. Giving Kemba Walker $35M a year to fill the IT/Kyrie role is absolutely retarded. That's not a void that needed to be filled, and it does nothing to change the team for the better. All this is going to do is perpetuate the dynamic of the last three years where everyone stands around holding their dicks, waiting for the "all-star" point guard to do something. They could have signed Patrick Beverley, a much more useful player for our current roster, for much less money.
Trading out D'Angelo Russell for Kyrie is a lateral move for Brooklyn. Adding Jordan makes them marginally better I guess. Durant will be 32 by the time he's ready to play again, and even with him they don't have a championship caliber team.
The Sixers got better, they might be the favorite in the East even if Kawhi stays in Toronto. Losing someone like Butler hurts, but they kept Tobias Harris, and they came out ahead by replacing Butler with Horford and Josh Richardson, two of the better support players in the league.