Sometime in the past in discussions about tea kettles, we deemed the Zojirushi and others with several temperature choices practical, but thought about a product that would allow us to choose the temperature at which the water settled. Looking over the Nothing But Tea web site this morning, I found two variable temperature kettles I hadn't seen before that allow you to choose water temperature, both sadly out of stock, but it's a start.
They are toward the bottom of the page.
Cross-posted to TeaDisc because I don't quite remember where that previoius discussion took place.
Michael