Jim also said in that interview part of the point of Battle Ground was clearing some characters out. Too many for him to keep track of.
But he only directly killed off Hendricks and Murphy. Murphy was a significant character, but Hendricks, not so much. Hendricks had the potential to be really interesting, if this series was about the rise and fall of Gentleman John Marcone. Seeing as it isn't, he was just fun window dressing. We could speculate that Hendricks might have a greater role to play; for example, if he had been the one to pick up Thorned Namshiel's coin, but then he might have overshadowed his boss, so Jim was never going to do that. I'm not going to go into removing Murphy, as that discussion has been held elsewhere.
As far as minor characters who died off-stage, I don't know that I really care. If Nick Christian and Mike Atagi died off stage, all it means is that Harry will be sad about a couple of other friends who died and he will have to find someone else to fix his car; who we will also never see in any of the books.
The only other characters who were at absolutely at risk (that I can recall) are the book seller Artemis Bock, the EMT Lamar and Detective (or Officer) Rawlins. I don't want to find out that any of them died, but it wouldn't throw the story out of whack if any of them did. The only offscreen minor character whose death might have significance would be Mortimer Lindquist. His death would remove Harry's ghost whisperer and it's still possible Mort could still play a role somewhere down the line. (Though I doubt it.)
I'm just not seeing the necessity for Jim to kill off minor characters who complicate the story because so few of them do that or have the potential to do that.
Which is odd, because most of the powerhouses - the immortals, the KotC, and the Senior Council members - were badly wounded but survived. Karrin and Hendricks are benched, but if Ragnarok is included in the BAT, presumably that's going to supersede 'until nobody alive remembers them'. Thomas is benched, but can be brought back when the time is right. The B team wardens are dead, but undead and presumably enemies now.
This didn't really prune a lot of threads, it just put characters on the shelf for a while.
I've thought the same thing, but then I remember that all the Einherjar will permanently die with Odin at Ragnarok, so even if Jim brings them back, it won't be for long.
