There is no better word to use than nicheification. This neologism is nicely introduced and explained in the article. What we have here is practically a textbook example of how to insert your neologism into discourse, and the author should be applauded.
Unlike specialization, nicheification carries that added connotation of painting oneself into a corner, which is exactly what is desired.
(An alternative point of view to the article is that as a niche player your chances of surviving the next round of corporate restructuring go up. A lovely short-short story by Georg M. Oswald in last week's Frankfurter Allgemeine Zeitung satirizes this outlook on life. It's in German but since it's only a page long I can summarize the plot: Timid guy trembles as he is called into boss's office, expecting to get the axe. Boss tells him he's safe because he is a "niche man" -- the type of individual who seeks out a spot of terrain that no one will contest (because it is unattractive). Timid guy slinks back to his desk, thinks about phoning his wife to complain, but soon goes back to working as usual.)