There's a huge difference between what one advocates as a position as a politician trying to get/stay elected in a two-party democracy, and what they'd be willing to force through if they were all-powerful.

As an example, do you think that, given the ability to enact whatever legal changes he wanted, Bernie Sanders would nationalize our telecommunications infrastructure? Or our health care system?

I don't have any specific, citable reason to think he would, but I think there's plenty of reason to believe they're things he might want to do.