Will BootCamp continue to be supported for the next ten years on my June 2019 MacBook Pro so I can install an operating system that continues to develop new features with the assumption I'm running on x86-64?
I mean, there's nothing too magical about boot camp—even if apple removed all support for it from macOS, you can probably install windows on a partition the normal way without too much trouble. I think the only thing that might break is if Windows stopped being compatible with the Mac hardware drivers, and Apple didn't update them.
What do you mean by "continue to be supported"? Your 2019 MBP will only need new drivers for Windows if Microsoft decides to change things. Otherwise, Apple doesn't have to do anything at all for your current MBP to continue to be able to run Windows. While Windows may be something of a moving target, your particular machine isn't.
