If they feel okay trading him they obviously aren’t sweating it. By “anyone” I mean a player good enough to make BB’s roster in the first place. They have been able to find versatile ST players with regularity in the late rounds and after the draft. I trust Belichick implicitly—in this case to easily find someone to replace Richards. Don’t need to be told that he cares about special teams.
I think it says something that they kept Richards on the roster for three years and played him as much as they did on ST, but you're right that it also says something that they were willing to trade him now. Also worth noting: they save almost $1 MM trading Richards; he was going to be a good chunk more expensive than guys like Grissom or Bolden or Christian Sam (though not a lot of money in absolute terms).
For the Pats, kickoffs are still more about Ghost popping them up inside the 5 with regularity.
The coverage has to complement the kickoff strategy or it's not going to pay off. I agree Gostkowski is the most irreplaceable part of the formula but the coverage still matters, and the better the coverage is, the closer to the goal line they can pin down the other team.
This was a big part of last year's team: the Patriots kicked off 3rd-most in the NFL and their opponents had the worst or second-worst starting field position post-kickoff. Because of this and because they had an effective O that didn't turn the ball over, their opponents had the worst starting field position by a full yard, which was a big factor in the D's statistical success.
