Not sure why this can't be a K1 also. Shield tablet scores almost the same (a bit better) at 3276 and is 64bit if Denver is used.
http://browser.primatelabs.com/android-benchmarks
Also the single core score was 1091 for shield tablet vs. 1040 here for shamu nexus 6 unit, so it seems you could go either way perf wise at least in geekbench. Do we really know what this SOC is yet (in a shipping unit that is, despite geekbench unit showing qcom) without an FCC filing (or did I miss that)?
Since shield tablet has an LTE version now, I guess you could even see a multi part launch like Samsung does (where Qcom is used in 1/2 the world and samsung soc used in the other 1/2), where they may use Qcom in 1/2 and K1 in the other to ensure enough chips for a big launch, or split them for 32bit on a cheaper one and 64bit on the K1 version (clearly the better gamer). If I was google, I'd want Denver for 64bit, as that is a selling point (along with the best gaming soc out there) even if it doesn't mean much today.
To the public at large, they still think 64 is twice as big as 32...LOL. Sad but true, and that will sell units and make your device unique on android, just like Apple currently can brag about this and they have it as one of their selling points on the apple website. If the nexus 9 is 64bit, I can't see why you'd want to hamper sales with a S805 shipping AndroidL. People will look at it vs. the nexus 9 and wonder why there are no claims of 64bit for nexus 6. I don't know why google would hamper gaming AND ditch the opportunity to claim 64bit. Those are BOTH big selling points (even if the 64bit is ..meh for now in reality).
IF they don't sell a 64bit one with Denver (considering this comes AFTER the nexus 9 which is supposed to have Denver), then yes, I agree nexus 6 will be a partial dud at best. Someone WILL release a 6/7in with Denver/64bit and that will be the end of Nexus 6 sales IMHO.