Discontinuing models - What's going on?

...the effect of emissions by new motorcycles was statistically insignificant, I don't see that happening elsewhere.
In the US - I guess so. And I agree with you.

But here two-wheelers SOARED in sales (well scooters) when Europe deemed that you can ride a 125cc without any form of M/C licence - just a car licence. I know the secretary of the M/C mfrs guild here and he showed me the numbers - there was a moment more scooters were sold/week than refrigerators. Spain has pretty good weather most of the year and salaries are low. Most scooters therefore are also POORLY maintained and thrashed. Result clouds of smoke and CO. I don't know but sub 125cc probably form close to 50% of the 2 wheel pool if not more. The exception has been the Piaggio MP3 which having 3 wheels is classified as a "light Tricycle" so the engine can be bigger without need for an M/C endorsement. But they're expensive so also tend to be well maintained. There is also a Hibrid.

The legislation is designed to generate renewal of the motor pool as well - keeping industry active. But ime - here anyway - fails.

ime here - all the emissions pressure does is ensure the survival of more Classics. Bikes (and cars) that would have been scrapped 5-10 years ago now command a premium.
I have been offered really SILLY money (pretty much the cost of a NEW R3) for my 1979 Guzzi and also 400% book value for my 1994 Land Rover Discovery with mechanical FI.
Both pre-date emission control law of 1997. You've guessed - I'm not selling.

I only know of one country that backdated-dated emissions compliance - Germany. Was a time you could pick up 5L Merc's for export at minimal cost.