Following a trend.....Yamaha keeps a model in production, for about 3 1/2 years to 4....it would be very expensive to change models every year...R&D, Design, marketing, etc...the same was for the Electones, and also is for the Clavinovas.
The PSR 3000 hit the stores almost a year ago, if I am not mistaking (depending of the area),in Phoenix (Az) arrived in the last half of october.
The price drop of the PSR 1500 perhaps is because is a slow seller compared to the 3000.