The drop in younger riders getting into bikes has been widely reported in the UK motorcycle press, so I'm just repeating what I've read. Maybe the situation is different over the pond? As I mentioned, the older riders are moving away from uncomfortable sports bikes and moving to nakeds and adventure bikes. That is a fact over here.
My theory about rider aids wasn't connected with younger riders. In fact quite the opposite, as a top line 1,000cc sports bike costs a significant amount of money, it's mostly mature riders who buy them. Mature and sensible(ish!), hence why I suggest my theory that these sensible riders used to buy 600's because they felt a 1,000 was too much to handle. But now the electronics have tamed them, they are more confident to ride them.
Whatever the reason, sales of 600 sports bikes have been in rapid decline and the discontinuation of the CBR600RR has been reported in more than one UK bike publication. As I mentioned, it's a fact that only 100 R6's were sold in the UK last year. Also Yamaha haven't changed the latest R6 bike since it was introduced. And that's about 5 or 6 years I think. That's a long time in the bike production world.
Certainly the economy will have an effect on bike sales I agree. But litre bike sales are doing pretty well.