Horford / Timelord
Giannis
Richardson
Smart
Schroder / Pritchard
If we still had Fournier, I might consider it. 
The spacing on that team makes me unwell (without a Fournier-type)
my thinking too. they'd make noise in the East but unless Pritchard, Nesmith and Romeo all develop significantly going into the season where they're hitting outside shots consistently, they're not winning it all.
So you have a down year where you only win a round or two in the playoffs and then you regroup in the summer with the best player in the sport who is signed long term. Not a bad place to be.
And I do think they'd have a shot (the trade with the enough salary that is the simplest to do is Giannis/Connaughton for Tatum/Brown).
PG - Schroder, Pritchard, Dunn
SG - Smart, Connaughton, Langford
SF - Richardson, Nesmith
PF - Giannis, Parker, Williams
C - Horford, Williams, Kanter, Fernando
cut Edwards
I think that team would have a real shot this year, but would be in pretty good shape next summer with Horford and draft picks available to acquire a better running mate for Giannis.
If you can acquire the best player in the world, you have to. Every time, without question.
How would that Celtics team get past that stacked Bucks squad, not to mention the Nets?
It would obviously be a challenge this season, which is what I acknowledged, but going forward I wouldn't be worried about finding a running mate for Giannis.
And I know that Tatum and Brown are better now, but a much worse Bucks team ran through a much better Celtics team not that long ago in the playoffs. That 2019 Bucks team was Giannis, Middleton, Bledsoe, Mirotic, Lopez, Hill, Connaughton, Illyasova and they just steamrolled Irving, Brown, Tatum, Hayward, Morris, Horford, Baynes, and Rozier (Smart was mostly injured). And they did so because Boston had no one that could guard Giannis, which would hold true for that Bucks team. Giannis would destroy Tatum (which not coincidently is an example of why I hate Tatum at PF) on both ends of the floor over the course of a series, and without Tatum I wouldn't be all that worried about the Bucks and their plethora of #3 type players.
The Nets are on borrowed time. Maybe they are all actually healthy for a playoff run, but good chance they aren't, because those guys are never healthy for long (Harden has been pretty healthy in his career, but he does have a lot of miles on his legs and is at the point when most people really start breaking down). Either way, I don't think the Nets have more than a year or two window.
If you can acquire the best player in the world, who happens to still be in his mid-20's, and signed long term, you have to. Every single time, without question. Talent wins in the NBA, you acquire the talent and figure out the rest later.