The top 10 PGs in the league right now are impressive - Steph, Lillard, Haliburton, J Murray, D Fox, Morant, Trae, Garland, Brunson and Kyrie.
Next group contains all 3 of Boston's combo guards. So Smart, D White, Brogdon, CP3, Jrue Holiday (tops the group), VanVleet, McCollum, Conley. Then guys like Rozier, maybe D'Angelo Russell, Dinwiddie but they're a notch below the first group mentioned. Not sure whether Jrue should be added to the top group and expanded to 11 or no. Anyway.
The idea here is that Boston could make a lateral move for similar talent but more natural PG (Conley is a good example). But if they want a talent upgrade, they gotta go after one of those top 10 guys. I don't think they can get any of them without giving up Jaylen Brown. They're too good. They won't be available for anything less than Jaylen.
Garland may be the easiest to pry loose. Lillard is possible. Maybe Morant. Memphis seem pretty p---ed off at him. Trae another option as Atlanta tries to figure out how to move forwards.
Haliburton, Steph, J Murray, D Fox all look too difficult to pry away from their teams. Probably Brunson as well.
Kyrie is somewhat possible but I don't want to go down that road again. Not at a high price. Maybe at a low price like Smart and filler. But that won't be on the table. It'll be a high price or no deal. They'd rather keep Kyrie.