This question has been asked at least twice before but bear with me.
My main driver is a Volvo 850 T5 estate which reaches 0-60 mph in about 7 seconds. That's not too shoddy for such a heavy car.
I've been driving my friend's car, a Fiat 500 electric and whilst I've not pushed it to the limit, hitting the accelerator (gas pedal), it is no slouch, not as fast as the Volvo but you know there is power if you need to overtake.
Now electric motors can produce high torque at low rpm, an ICE needs more TIME to wind up the rpm's, that is why a fairly mundane model Tesla can embarrass a Porsche 911.
For various reasons petrol and diesel engined cars are considered to be the spawn of satan and manufacturers are moving over to electric vehicles.
I am guessing the 2nd gen did not sell well enough so Yamaha canned it.
To develop a gen 3 ICE I suspect will take a huge sum of money, be expensive to buy so won't sell. I also suspect that once batteries reach sufficient power to weight ratio, it will be cheaper to design a motorcycle around an electric motor than develop a more powerful engine than the gen 2.
So in my opinion, if there is a gen 3, it will be electric.
Phew.