As far as adoption is concerned, I'm not sure it should be that big of a concern.

After all, D is supported by GCC and Clang and continually being maintained, and if updates stopped coming at some point in the future, anyone who knew a bit of C / Java / insert language here could easily port it to their language of choice.

Meanwhile, its syntax is more expressive than many other compiled languages, the library is feature-rich and fairly tidy, and for me it's been a joy to use.

GCC usually drops frontends if there are no maintainers around, it already happened to gcj, and I am waiting for the same to happen to gccgo any time now, as it has hardly gotten any updates since Go 1.18.

The team is quite small and mostly volunteers, so there is the question how long can Walter Bright keep at it, and who will keep it going afterwards when he passes the torch.

It has an LLVM backend, LDC, that is separate from the LLVM project/Clang.