The companies using Azure Stack today are some of the least likely to be parroting that fact. Microsoft's on-prem is pretty well entrenched, particularly in "boring enterprise" where pragmatism beats idealism, are quiet "do the work, don't leak the work" more than proudly proclaim to be chasing the trends.
That said, Azure Stack (and Azure) already have strong Docker support, without an acquisition to date.
More interestingly, in my opinion, though, is that right now Azure Functions is the only "serverless" runtime with a strong open source story, and equally strong on-prem (both as part of Azure Stack and, increasingly from what I hear, standalone) as well as Cloud support.