More importantly, does it contain an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp? If not then I really don't see it having a future.
Yes, any good language can be obfuscated by converting to JS.
It's got an LLVM backend so yes. Probably not production ready.
What can't?
True--in principle any language can be executed in the JS runtime. A lot of them can even be executed reasonably quickly. Though I suppose the parent comment was asking whether a mature compiler from D to JS currently exists.