I agree with you that what we seem to need is some shooting on the perimeter, a big and possibly a 'vet' PG. I am putting the unknowns in parentheses.
Exum - (stopgap backup/vet) - Cotton
Burks - (shooting wing) - Millsap
Hayward - Hood - Jingles
Favors - Booker/(back up big)
Gobert - (Tomic)/(back up big)
Notes:
(stopgap backup/vet)* - I think right now we are forced to give Burke starter minutes as a backup. I feel like we can do better than that and if we need a PG to play starter's minutes off the bench, I'd be looking at someone like Cory Joseph or vet in free agency to take on that role while we are waiting on Exum to be ready for full-time starter minutes and responsibility.
(shooting wing) - depending on what level of SG we are able to get, he might move ahead of Burks on the depth chart(for example if by some miracle we are able to steal a Danny Green type of player in free agency), if we do it in the draft he gets slotted behind Burks and ahead of Millsap in the depth chart.
(backup big) - if we trade for our shooting wing(or if we give a lot of money to FAs), chances are Booker would have to go, thus we probably would need to draft a big - Kaminsky/Portis/Looney(if we don't trade the pick), or Jarell Martin type(if we trade the first round pick).
(Tomic) - that's the big known-unknown. Again if he doesn't come over this season, chances are he never will and we can scratch him off our minds forever, If he doesn't come we might have to look into drafting a center - Poeltl/Turner/Kaminsky
There are a lot of unknowns and a lot of possible combinations, thus it's really hard to build a reliable depth-chart for next season. One thing is for sure - our FO has some choices to make this summer... the good thing is we seem to have options to choose from.