Gillette is actively trying to push people off of Mach 3 (and most of their advertisements specifically show people who stop using it and switch to the newest "Fusion" model)
But they definitely push for whatever is the newest (and usually more expensive) option.
(I'd like to see priceonomics write a blog post about the razor blade model)
http://www.theonion.com/articles/fuck-everything-were-doing-...