I've never honestly outside of Sega's MTV style marketing of the early 1990s seen a marketing campaign actually turn around a systems fortunes, and really the Sega marketing worked primarily because they had Sonic, which was something and fresh to counter Mario with.
Advertising a product that people don't want in the first place doesn't magically make them want it. There are 160+ million PS3/360 owners, Nintendo making another PS3/360 class system and getting crappy third party support on top of that, simply does not appeal to a lot of people.
The market for the home console is all in the West nowadays, and it's all the core gamer segment. Casuals went off to mobile and the Japanese aren't interested in consoles period. Nintendo basically made a console that was banking heavily on two audiences IMO that don't want a home console anymore.
Sega had a big marketing push for the Saturn in 1995, but it didn't do zilch for the system.
