The time is now. Horford's 29. Our other guys, whoever we would keep, aren't so young either.
We've been accumulating these assets with the goal of getting a top 10 player. Russell is one.
If we end up moving a significant share of our young guys and picks, so be it. We will surely retain enough other assets of medium value, and the higher cap along with our existing set of players means we can still pickup the 2B to Horford's 2A if need be.
And once we have those guys, we will be a destination for the David Wests of the world who will sign for peanuts in order to win. Concerns about depth are overblown and picking up 6th-10th men is a heckuva lot easier than getting an MVP-level player.
Giving up both Brooklyn picks is not too high a price. Even in a deep 2017 draft, that BKN pick has about a 10% chance of getting you someone as good as or better than Westbrook, and the odds are even worse in 2018.
If we can do this without breaking up the core of the current rotation, it should be done