Just irt the defense...
They need to find two safeties. Not too difficult to do that, as they could potentially add one on the cheap in FA and then draft a couple mid to late rounds among all those comp picks. Generally speaking safeties with good coaching can translate quickly if you play them the way they showed their best in college. Rams executed a cheap safety reload prior to Staley's first season and it paid off big time that season for us. So not too worried about them regardless of who leaves.
They need two corners who fit whatever scheme Raheem wants to call. This is with the assumption Ramsey is dealt. Durant is a good piece that works at 1 of the 3 "starting" corner positions. If he can play outside then maybe Kendrick settles in the slot and we're not so short in year two as both improve. Kendrick playing outside the hash was not his fault. That was on the coaching. But regardless just to be safe we need turnover back there so two corners feels right to me if Ramsey is dealt. Then you have better depth and are not relying on Kendrick. This is probably our biggest need, simply because of how unlikely it is we find a top edge this offseason. We need to rebuild this group so they can cover. Which is what they did not do the past two seasons, they just had a rush covering them during the SB run.
They need two edge additions if Floyd is dealt. Chances are those additions will be good contain and run game types at the least, as you can find them and this is why they're going to cut bait on Floyd. The hard ones to find are the rush specialists, the guys with the instincts to get pressure. Maybe we get lucky there, maybe not. But two additions are required and they'll probably be the types we need to hold up vs run games in the division.
So that's 6 additions. If we assume they bring in a cheap FA at safety or edge (dice roll type) then we're talking 5 picks spent on the defense at a minimum. It isn't easy to hit on that many additions. So let's assume 3 of them can impact in primary roles. We're probably going to be one of those defenses that has a few holes. Edit also let me add that if we're lucky some of our holdover talent develops better, which could positively affect all this.
On top of that you have questions at DC. Raheem needs to have a great season. I don't think he is dumb, he's a smart dude and you can tell in the way he speaks, but he has to do better for this defense to have a resurgence given the above. He's gonna need to improve in particular in pre-snap mind games with QBs. You just cannot line up at this level vs these QBs and do well if they're not confused at least a little bit. Not without top players at most positions which is hard to pull off.
Looking at the secondary/staff moves Raheem is going to have much better support around him to ensure he's ready on gameday for each opponent. I don't expect coaching to be an issue basically. We don't have an elite DC unfortunately but we won a SB with Raheem so let's focus on getting him the right pieces for him to call it how he wants this season.