My thought is if the Jordan Bulls didn't make the Finals the year he returned mid-season, then it's almost impossible to do.
I'm saying ECF.
This is more or less where I fall - unless Tatum is an absolute supernova in the postseason, I don't know if we make it out of the east.
The difference is that the Jordan Bulls were 34-31 when Jordan returned, before going 13-4 after he came back. So he elevated them from a probable 1st round exit to ECF. The Celtics are currently the 2-seed through 2/3 of the season, so ECF without Tatum is a reasonable expectation, and would probably come down to matchups in the earlier rounds. Now, Tatum is also not Jordan, of course, and he is not going to score 55 points 10 days after returning, but I think the more important point is these Celtics are far better than the 95 Bulls were. The only reason the are not several games ahead of the Knicks is those first three weeks of the season when the team was still figuring itself out. Over the last 41 games, they have the same record as the Thunder and Spurs and are one game off the Pistons. Their net rating of 8.4 is far closer to the Pistons at 9.0 than it is the Knicks at 5.8.
So while 95 Jordan > hypothetical 26 Tatum, 26 Tatumless Celtics >> than 95 Jordanless Bulls, and therefore 26 Tatum Celtics > 95 Jordan Bulls.