Is a PhD in TCS the best way towards achieving a career in industrial research?
The comments are all pretty spot on (and maybe they should be answers). To add to them: 

In industrial research of the Google/Yahoo!/AT&amp;T/MSR/IBM variety, there are definitely specific area interests, but there's also interest in people with broad interests and strong foundations. A Ph.D in TCS can provide such a broad set of interests and a strong foundation if you choose the right topics. 

So for example you could do a Ph.D in computational geometry, focusing on combinatorial problems in incidence geometry, or you could focus on approximate high dimensional algorithms. It's possible that the second topic might allow you to "sell" yourself more effectively as a data analyst, especially if you can point to some awareness of the applications of your work (some papers etc). 

So even if you were to do a Ph.D in TCS as a path towards industrial research, the success of this plan really depends on the kinds of topics you choose. In the long term, I think it'll make you very flexible and able to work on a variety of things, but you'll have to seek out that breadth during your education.