Let me sketch out how we could have a strong competitive team in 2017 even while stopping after the Heyward deal.
1st Freeman
2nd Peraza
SS Simmons
3B Kubitza/Castro platoon
C Acquired or Signed
RF Um Markakis
CF Acquired or signed (main trade bait is Gattis)
LF Acquired or signed (main trade bait is Gattis)
Starting rotation: Wood, Miller, Teheran, Perez, (one of Jenkins, Sims, Martin or Hale) with the others providing depth/bullpen help
Closer: Kimbrel
In this scenario we make one big signing to fill one outfield spot. I believe we all agree payroll can go up to allow for this to happen. Gattis is used to acquire the second outfielder in a trade. I bet we even have money left over in this scenario (since we are not paying Justin Upton or Heyward to stay with the team) to pick up a solid veteran starting pitcher.
It is worth noting that even with all the prospects we have picked up, there is a general consensus we are going to have to spend to get a power bat to play left or third. So in that regard, projecting we are going to spend there is the same in both scenarios. In both scenarios there is also a need for a catcher.