I don't think the younger crowd will come around, at least not to the kind of motorcycling we're used to. Cruisers actually aren't always popular; motorcycle sales, with a couple of outliers, are down across the board. HD, the kind of cruiser makers, has lost about 16 percent of their sales in the past two years and has shut down factories in both the US and Australia, with no end to the downward spiral in sight. I believe that BMW is the only manufacturer to post sales gains in the past two years. There are a bunch of reasons that the sport is declining, but a couple big ones are debt load for the potential new generation of riders, and simply a change in perception of motorcycling in general. Twenty somethings don't have the same interest in it as we did when we were that age; hell, there's even a downward swing in how many younger people even bother getting their drivers' licenses, let alone motorcycle licenses. A generation that looks forward to self driving cars isn't going to have a lot of interest in the far more visceral experience of riding a bike. Plus, a lot of this crop of potential new riders are saddled with five and six figures worth of college debt, which they're going to be carrying well into their thirties or longer; that doesn't leave a lot of wiggle room to buy what a lot of people consider to be a really expensive toy. If motorcycling has a future with the upcoming generation of riders, it may involve a lot more smaller displacement, cheaper bikes, or electric bikes, or maybe even self driving bikes.
I think a lot of us forget that in the approximately 115 year history of motorcycling in the US, it's only been generally popular with the masses for about fifty of those years; basically starting with the Japanese invasion in the 60's, up through the explosive growth of Harley in the early 80's after the buyout. A lot of that boom directly coincides with the surging middle class prosperity of the Boomer generation and the Gen X'ers that were riding on their coattails. Up until the whole "you meet the nicest people on a Honda" ad campaigns, motorcycling didn't have mass across the board appeal. It was looked on at best as a frivolous pursuit for perpetual adolescents, or at worst as a hobby for drunken hooligans. Motorcycling got really popular both because prosperity made it possible to afford one, and the culture changed enough to make them generally socially acceptable. The cultural shift that made them generally acceptable and desirable can go in the opposite direction, too; maybe that's what we're all seeing happening right now.