It does look like this is the supposed "BIG" price drop that we all thought would happen this year...although it's not quite big enough.
Seeing as the 20Gb model was $499 and people still didn't really buy them...I reckon making the price now $499 won't really do much for sales.
I reckon, they need to bundle a game with them....what about Motorstorm or Resistance as a freebie along with a nice BluRay DVD as well all for $499...then maybe you will catch a few more buys.
Prediction (June 12th 2017)
Permanent pricedrop for both PS4 Slim and PS4 Pro in October.
PS4 Slim $249 (October 2017)
PS4 Pro $349 (October 2017)