FWIW, Woj was on ESPN radio this morning and said Tatum is the most valuable chip available, including a potential #1 pick.
I think this is one of those things that's situationally true. It's very likely true to the extent that Boston is a team that's going to bid on Davis and they actually have the prime asset (Tatum) in possession. The Knicks and Clippers are going to get in on the bidding, but neither one of them has the #1 pick, and there's no guarantee that whoever does get it will have any interest in trading it for Davis (the Cadavaliers, for example).
And I can see why the Pelicans are spreading that rumor, you don't want the other suitors, if they land Williamson, getting the idea that that's enough. They want the Knicks or Clippers pushing everything into the middle of the table if the ping pong balls bounce their way.
But in a vacuum, I suspect that Williamson has more value to Demps than Tatum because the extra two years give him a margin of error in rebuilding. If he takes Tatum he has four years to build a winner before ending right back here. And because his centerpiece will be a third year player, people will expect results on day one.
And the reality is that Tatum really is good enough to carry the Pelicans into the late lottery territory, meaning that the Pels' next shot at the high lottery will come as Tatum is signing his rookie extension (the Memphis pick assuming they get it). Then he has two years. Williamson at least gives him six years to build around, and with the promise that New Orleans will be adding high lottery talent to him in 2020.
So if New York lands #1 I expect Davis to end up there for Williamson, Knox, and DSJ. Boston could outbid that by emptying the cupboard (Tatum, Brown, Rozier, Sacramento #1, Memphis #1), but I'm not sure I'd make that bet. If he leaves you're more or less screwed.