I think it comes down to 2 things:
1. Does Exum become a starting caliber PG?
2. Do 1 of Exum, Burks, Hayward, or Hood become a a legitimate #1 scoring option?
I would be very surprised if Exum doesn't become a starting caliber PG (at the very minimum), even if it takes a couple of years for that to happen. The x-factor is if Exum develops into a full fledged star. If he does, then we may just be able to get by without having a true #1 scoring option (assuming that Exum becomes a star based on his defense, passing, & solid but not elite offense), due to the fact that Hayward has proven himself as a reliable #2 option, while both Burks & Hood have that type of offensive potential (& even Favors could become a #3 type offensive option on a championship caliber team). Like others have already said, a lot of this comes down to what type of player Exum becomes (especially on the offensive side of the ball).
If Exum becomes an offensive threat, then we may be able to become an offense by committee type of team that is good enough to get by when we combine that with an elite defense. If he doesn't, then I think we would still be short a go-to-scorer (which I don't foresee any of those players becoming). Just to be sure, I think we should do everything possible (outside of trading our core) to add a player with that type of offensive potential, to go along with the players you have listed (although I think we could do without Burke at this point).