If you look at all the teams who have won the SB's recently (except the Patriots**, but they are a different story and were lucky that they were given 2 SB's), they did it with strong defenses and a good but not stellar offense. Right now, we have all our stars on offense. That's often good to win games during the regular season and to reach the play-offs, but there it usually ends. On defense we only have Heyward, Watt and Haden (and he's often injured) who are good. All the rest (including Tuitt) are mediocre at best. You can have 2 or 3 starters in your team of that quality, but not 8 or 9 like we have. Maybe better coaching can help, but players like Dupree, Burns, Davis, VW,... have a limited ceiling.
If we want to have a chance to sniff at a SB again I believe we should shift from going offense to defense. That doesn't mean we have to neglect our offense, but we will need to rely more on our young (and cheap) players like Juju, Conner and Washington. The OL and maybe the QB (but not a 100M) are the only ones I would pay on offense. It's not a complete rebuild as I think we already have a good OL and some young talented players. We can also hold on to Ben until Dobbs or Rudolph can take over in a year or two. We can't trade AB this year since they've restructured his contract (it would cost us 28M in dead cap), and also in 2019 it would cost us a lot of money.
We should focus on defense, through the draft and in FA. We have a lot of cap space, 14M and counting thanks to Bell's holdout (I hope he's not coming back before week 10), we will have about 20M in cap space. That should be enough to acquire 2 really good defensive players (I don't care which position) in FA. Get the best defensive player available in the draft and even trade up a couple of spots if a really good one is dropping to the middle of the first round, like Derwin James this year. Quality is more important than quantity, since our depth is already good at a lot of positions.