Tatum is the borderline superstar, Brown is more like a borderline star. I'd classify him as a complementary one to be exact.
Exactly. There's just not enough collective ball handling/playmaking in the Tatum/Brown duo to ever feel confident in their getting over the hump, nor enough sheer star power to render that moot.
They'd be the favorites with this and if they win a championship(s), between that, being a big/historical market and having prime Tatum and quality role players, they should be able to eventually attract another star to replace Durant.
The Celtics will obviously have to add picks/swaps, but realistically no one is beating that base, which is why they'd be wise to hold firm on White instead of Smart.