Seems like the rich & poor did very well in the last few years. Cars like GT-R's & other even higher priced cars will do well. The mid class, your biggest Z buying group has shrunk & getting smaller.
There are very few good paying jobs waiting for the young college graduates. The 350z & 370z was bought by many people in their twenties. Today very few people in their twenties can afford $30k-$40k cars.
I'm sure the car producers are aware of the market change. They have to be!
So I think the Z will get smaller & cheaper. My opinion is don't get rid of your 370's so fast