I think UGA's passing game will be fine. You're right about losing King - the leading WR. However, Michael Bennett was leading the team in receptions and yards when he went out with torn ACL but will be back next year. Malcolm Mitchell played CB for 4 games but finished the season with 2 less catches than King. Both TEs return and Conley, Wooten and others played a lot and looked good. Scott-Wesley looked good in the bowl game. Gurley and Marshall (remember his TD catch in bowl game?) both catch well out of the backfield. Oline returns, as will two leading FBs. If Murray returns, the offense will be better than this year.
And the rushing game should be solid with Gurley and Marshall.
The defense will be a huge question mark. However, last year's #6 in the SEC unit was disappointing and underperformed...so it's not like UGA is trying to replace a top 5 defense.