Seems far more likely that Fournier won't be back as I don't think they want to pay the luxury tax for a team that is still below the top tier teams in the league.
Current Roster is taking shape
PG - Smart, Dunn, Pritchard, Edwards
SG - Richardson, Langford
SF - Brown, Nesmith
PF - Tatum, Parker, G. Williams, Fernando
C - Horford, R. Williams, Brown
That is 15 players and is just below the tax.
I don't like Tatum as having to play PF or Smart being the main PG, but with the current roster that is what we are left with. Now if the team can turn Smart, Edwards, G. Williams into a legit starting PG I think that would help balance the roster out some. Maybe it is Ball or maybe it is someone that doesn't require a sign and trade hamstringing the roster.
Maybe something like this
Rubio, Nance
for
Smart, Edwards, G. Williams, Langford, Parker
So do that trade and here is the roster with 3 open spots
PG - Rubio, Dunn, Pritchard
SG - Brown, Richardson
SF - Tatum, Nesmith
PF - Nance, Fernando
C - Horford, R. Williams, Brown
Team seems a bit more balanced and then Tatum isn't out of position all game every game (still will play PF, but Nance starts taking some burden off him) and there is still a lot of flexibility with the 3 open roster spots (and Fournier could still be brought back if the tax wasn't an issue).