Year old factory bikes?

So, the Dean Wilson deal had me thinking. With as little as the bikes change from year to year, how much of the factory stuff gets brought over to the following year? If it's little to nothing, why? Why wouldn't Husky take parts from Dean's 2018 bikes and let him use it (support role) on 2019 bikes that he purchases himself? Obviously engines and such may be totally worn out, but what about suspension, foot pegs, or other "factory" items that could be transferred? If these items aren't being used, would this be of benefit?