Teams leery of trading for Lillard with multiple All-NBA players potentially becoming available within the year
Teams are leery of giving up assets for Lillard that might eliminate them from making a play for MVP level talents like Giannis Antetokounmpo, Joel Embiid, and Luka Doncic. Celtics-wise Stevens would 100% be interested in adding any of the three aforementioned players as all of them would fit nicely next to Jayson Tatum and would presumably be an upgrade over Jaylen Brown.
Of course a lot could happen in a year's time. Jaylen could make a leap into an MVP talent himself or injuries could lesson the value of Giannis, Luka, or Joel. It's very rare for a player of these three's caliber to become available still in their primes (or young primes with regards to Doncic), so next offseason could be a crazy one.