Well, it's hardly surprising that if you don't update it for 7 years, and you don't promote it, sales are going to plummet.
Funny that I'm pretty aware of the rear-wheel-drive sports coupe market, yet when it came to looking for one for my wife, I did't even think of the 370Z at first. Genesis coupe (about to be discontinued), Toyota 86, various Porsches, Miata and Fiata all came readily to mind. Muscle cars, too, although I quickly came to my senses there! It wasn't until I spied a used one that I even remembered the 370Z. I think it's just lazy business practices that are keeping the Z34 on life support. As MacCool said, it's paid for itself. Since new development costs money, why not just keep producing this for now with very few changes? It truly was one of the best cars you could buy for the money and the purpose. But the market is passing it by.
The Juke is a far more imperfect car, but well received for years. It's sales, too, have almost been halved. It probably is time for it to go.
Just because this series of each is coming to an end, doesn't mean goodbye forever though, does it? I don't know about Juke, but I'm sure this must have been posted here before:
Nissan Z Concept Coming; Production Car Could Reach 500 Horsepower
I recall a recent interview with some design person from Nissan, too, talking about how the Z was dimensionally bigger than its predecessors, and he implied that the next generation would be on a diet. That was promising news on several fronts. It probably means a smaller, turbocharged engine, but if the output is where it should be then that's not the worst thing in the world.
Yeah, electric, automated people-movers are the way of the future. Fortunately, not the immediate future, and I'm old enough that they are not likely to feature in my time horizon. Lets not lament the demise of the internal combustion engine just yet. Mark Twain's famous comment definitely applies to this thread.