Nonsense. Leftovers are the dealer's problem, not Yamaha's. The new models come out every year on schedule regardless of how many 1, 2, or 3 year-old models are still hanging around. When I bought my son's '06, I was offered a "screaming deal" on an '02 426, still in the crate.
Dealers do not 'buy' the bikes. They are 'floored' ( lease/loan) , through the manufactuer.
Some manufactuers take the bikes back from slow dealers, and ship them to better markets.
Some manf give the dealer a huge cost reduction to buy them outright, when they become 'stale'.
If they owned the bikes outright, there would be no rebates, markdowns or close-outs, as the margin at the dealer level is not anywhere big enough.