In terms of wildcard - yes. At the moment, Virtualmin requires DNS to be hosted on the same system. You could do non-wildcard and pass HTTP challenge though.
Besides, you could do it right now, by writing custom script.
We discussed it with @Jamie and possibly, one day in the future, we’ll add support for remote DNS verification, using API authentication for DNS providers. (Let’s Encrypt, GoDaddy and other). It shouldn’t be difficult to add as it requires only few extra params to be passed.