While Jimmy is a talented player, his importance to the performance of the D was amplified by the lack of quality depth at CB. There simply wasn't anyone to step up and fill the gap created by his absence. They thought Wright was that guy but we know how that worked out.
I think you're right that they plan for a complementary player to play beside him, but also plan for depth to step up when Smith goes down. The fall off just can't be as great as it was and I don't think they will ignore what that meant last year. Hope for the best, plan for the worst. But as you point out, they kicked the can down the road with him and that huge 2017 cap number somewhat limits the options.
Don't want to ignore Tavon in these scenarios either. While it seems that his size limits him a bit, I think he will be more than capable to fill in the #2 role in the future. His limitations were exposed last year, but another year's experience and better play from his counterpart on the outside should do wonders for his performance. I'm sure the plan is for him to play the slot, but you have to think he will improve with time and be an option on the outside as well.