My list of players I trade Tatum straight up for with no questions asked (irrespective of need) is dwindling by the week. Think I’m at the following:
Simmons
Embiid
Porzingis
LeBron
Greek Freak
Wall
Towns
Westbrook
Curry
Durant
Harden
Kawhi
Davis
It's a pretty interesting discussion, and basically hard to answer because Tatum's first 25 games compare well with any of those guys, but of course that's no guarantee he progresses as they did. I know WS/48 isn't a great measure, but as a quick comparison (and a per-game catch-all stat), looking for rookies (under 23, in the 3-pt era, with 25+ games and 20+min/game), WS/48:
Jordan .213
Faried .212
Tatum .198
Duncan .192
Ilgauskas .189
Jokic .185
Bird .182
Magic .180
The guys on that list who put up those numbers while playing 30+ min/game are Jordan, Tatum, Duncan, Bird, Magic. By BPM, Tatum's a bit lower (20th), but the list of guys around him is similarly impressive.
Now, there's a decent chance Tatum doesn't fit these criteria by the end of the year, and a near certainty he doesn't end up with a career anywhere near those guys, but I think the start he's had requires that you think hard about any deal he'd be included in, if you're also considering things like salary and years of control.