I'm not sure why you guys think Yamaha is fading away.....Spent 5 days over the past two weeks riding in the Newberry area and saw a ton of Yamaha's, both new and recent, almost all 4S except for a few SRX's and SXR's. I saw the usual Ski-Doo volume and noticed a small but visible number of the new AC's (front suspension is a dead giveaway). What I noticed the most though were all the Rush's, Rush Switchbacks, Rush Adventures and few of the new Indy's...and based on the colors most of these were 2012's and 2013's. Compared to 10 years ago when Polaris and AC seemed to dominate, there is much more of a balance between the 4, with AC being 4 now. Again, just my comments from 5 days of riding - nothing scientific about my survey. Your results may vary!
Noticed the same thing last week riding between Eagle River, WI and Copper Harbor - many more Yamahas than you'd expect given the presumed sale figures. Not sure why - do the Yamaha owners ride more the midwest, do they keep their sleds longer? I doubt they sell much in the West. With gas well over $4 all over the Keeweenaw, I know I started thinking more about a 4 stroke (or at least I will when it comes time to pay the credit card).
Provided the Viper turns out to be reliable, this seems to be a positive development for Yamaha - seems to fill a whole in its lineup and they didn't take anything out of it. I saw somewhere else that Yamaha will be introducing a sled to the lineup each year for the next 5 years. So I don't think they are going anywhere.