It's a great question, the right question to ask. We desperately need an upgrade in the front court. In the absence of being able to strike gold with our TPE and bring in a legit 3rd piece next to Tatum and Brown, I would seriously consider the following trade:
To the Celtics from OKC: Horford, Muscala and George Hill
To OKC from the Celtics: Hayward TPE, use out other TPE's, draft picks and a player or two.
Why:
1. If you're going to stick with Kemba for the next two years, might as well go in on Horford -their contracts would come up at the same time in two years.
2. Horford gives you a much better match up for Embiid, Giannis and AD should we get that far.
3. Muscala gives us some much needed size at the PF, and shooting.
4. George Hill would allow Smart to play some more three - Hill would meaningfully deepen our rotation.
5. You could then pursue another trade using Tristan Thompson to try and pry away some vet wing
Horford | Horford | Time Lord
Tatum | Muscala | Grant Williams
Brown | Ojeleye | Nesmith
Smart | Hill | Langford
Kemba | Teague | Pritchard
That team can play big or small, increases it's three point shooting and big man depth. It can win a title. OKC wants out of salary and draft picks.
I'd love to swing a deal to get that third star but in the absence of being able to do that, I'd pursue something like this. Tatum and Brown are capable of carrying us to a title but not if Ainge refuses to make moves to round out this team, particularly in the frontcourt. The othe rmove I'd seriously consider if I couldn't, A) get the thrid star with the TPE and players, picks, or B) swing the OKC deal above, would be to C) go after Drummond with the TPE and draft picks.
Drummond
Tatum
Brown
Smart
Kemba
With Theis, Thompson, Grant Williams, Time Lord, Ojeleye, Langofrd, Teague and Pritchard can also win a title.
My guess is Ainge does nothing though - short selling this team's shot at a title this year.