If the Braves didn't have Kemp, and if the rotation had 3-4 of the homegrown pitchers already producing 2+ WAR seasons, Stanton would be defensible as a win now move for the Braves. Pairing Freeman with Stanton pretty much guarantees an average offense or better.
However, just like it's unwise to waste assets (prospects) adding Quintana to this team at this point in time, it is unwise to waste assets (money) adding Stanton now as well.
At some point the Braves will be good enough to consolidate future value into present value, but now is not that time.
I think everything really hinges on what the payroll can really be. Coppy, Hart even JS have either directly said the payroll will go up or have said it in an indirect way. I can see ways to push the Braves to the front of the line, assuming they can add enough payroll (say, if they could push the payroll into the $150-$175M range). That is absolutely no given. It would squarely push the Braves into the top 10 payrolls in baseball, maybe even top 5.
And, the Braves would have to shed some of its bad contracts along the way, even some that are not so bad as far as money goes (Dickey, Markakis). Could they do those things? I would say it all starts with the money angle and how much payroll they are willing to take on.
And a lot depend on which clubs try to trim payroll and rebuild. The working assumption is that the Marlins will do that because they are losing money and have new ownership. That's not a given.
I am not saying they should go that way. But they could.
Let's say they sign Moustakas to play 3B (maybe 5 years $100M) (+20M)
Sign Arrieta to lead the rotation (5 years $125M) (+$25M)
Trade for Stanton (average of about $28M per year) (+$28M) Let's say it takes Folty, Sims, Wisler and Blair to get it done - certainly not talent for talent but Braves are taking all the money from Stanton.
Trade Markakis to move salary (~$10M)
Pick up $25M by letting Garcia, Colon and Dickey go
Then you have a net add of about $38M. Throw in rasises for the current team and you raise payroll by about $50M for 2018 net which should put the Braves in the neighborhood of $165M
You have a line-up of:
CF Inciarte
2B Albies
1B Freeman
3B Moustakas
RF Stanton
LF Kemp/Acuna
C Flowers
SS Swanson
Rotation: Arrieta, Teheran, a veteran low cost reclamation/place holder, Newcomb, Fried