Yes, UVU. And also yes. If I find myself needing something low-level and performant, I have a hard time justifying the ramp-up time required to use D since there is a near zero chance I would use it in my current or future employment. While that isn't always how I decide what technologies to use in my personal time, it definitely is a factor that tips the scales towards a more mainstream language
It is not a border, ofc. It is just a "mental concept"; and not a hard cut. There are villages/cities where both languages are spoken/understood. So one language spoken gradually changes into the other one.
