I think Nadella pulled them over and whispered in their ear.."hey man look, I'm trying to kill this Windows on a phone thing off. You can't be releasing new phones and messing up my plans. Remember, I know where you work"
or something close to that. Seriously though. I have no idea what is going on here. If it's due to a new feature then they won't be able to announce or release it for a while yet. As far as low, mid or high range, low end phones actually sold very well at 1 point. That's how Windows Phone was doing so well in other countries for a while back in 2014-2015. But, as you said, there's no money there and a company like WB, doing this on their own, simply cannot afford to go that route.
If Windows Phone is going to continue to exist, someone needs to take the place of Nokia, become the new Nokia. What I would like to see is for MS to embrace a company like WB, a company that has a passion for Windows Phone. Assist them with funding, marketing, and anything else they need while freeing MS of design and R&D. Make WB the premier Windows Phone company running Windows Phone as we always knew it. Then have MS release the Surface Phone which would be what we've been expecting, high end, a form of full Windows on it, etc.
I think there should be the normal Windows Phone for mid to low end devices and the new version of Windows on ARM for the high end. There has to be an upgrade path for the budget minded user and a high end devices for fans and enterprise.