They've done a SUPERB job of staying out of cap squeeze territory to this point, but the first crack in the dam on that front is ALWAYS something like restructuring Baldwin's deal. I'm not saying the sky's falling, but that's EXACTLY what the beginning of cap chaos looks like.
I'm guessing, however, that they would prefer to trade Sherman rather than any of the guys currently on the D-line if they're all playing at a high level. You get the kind of pressure we can expect to see from this group and you don't *need* a blanket corner shutting down 1/3 of the field. You run a press-man, bump-and-run scheme like the Seahawks already do, and mid-tier CB's will look great stats-wise at the end of the year with this D-line shredding pockets.
And like your namesake suggests, I think Sherman is an AMAZING player and I love what he does for the Seahawks. But his *marginal value* diminishes once you've got legitimate tops-in-the-NFL pocket pressure from the front four. If Richardson is part of the long-term plan (as I think he probably should be, assuming his play translates to the system--which I think it definitely will) then Sherman seems to be no better insulated against addition-by-subtraction than Bennet, Avril, or Richardson. If one of them declines this coming year and the rest keep producing at a high level, the question of who to let go answers itself.
The Seahawks are a SUPERIOR run team. It is a pleasure to watch them go about their business, isn't it?