A cash cow program? No. PhD programs are never cash cows.
I don't know why you couldn't be a professor with a PhD in data science. Rarely does a professor of a given course have to have a specific degree in order to teach it.
As far as publishing goes, there are any number of related journals that would accept papers from somebody on topics that would be covered by the topic of Data Science.
When I went to college, MIS, Computer Engineering, and Computer Science were new subjects. Most of the people in my graduating class for Computer Science couldn't program anything significant at graduation. Within a few years, CS programs around the country matured significantly.
When you are part of a new program, sometimes it's possible to help define what it is that's required for graduation. Being a part of that puts you in rare company for that field.
As far as mathematical rigor is concerned, I would expect Data Science to leverage a heavy dose of mathematically based material. I wouldn't expect anything particularly new - statistics, calculus, etc. should have been covered in undergrad. Masters and PhD programs should be more about applying that knowledge and not so much about learning it.