Kai worked on packaging Dub with the next LDC release.
https://github.com/ldc-developers/ldc/issues/1573

Hopefully, we can configure Dub such that it picks the LDC compiler it was packaged with (instead of a system compiler by default, likely to be dmd because Dub searches for dmd first). Sönke wrote a PR to enable using a defaultCompiler setting in dub's config file. But there is some doubt about how it should work exactly when multiple config files are in play. I do not have much understanding of common installation practice.
Please join the discussion here:
https://github.com/dlang/dub/pull/897

cheers,
  Johan