People will buy a decent system at a low price than a brilliant system at a high price.
It all comes down to price in the end.
The DS started well and has continued well because it has been cheap....yes it's a decent wee system, with some good games....but I don't see the PSP without good games as well.
If the PSP had released at the same price or just slightly higher than the DS then I think we'd be seeing totally different figures.
Sony has alienated buyers with the PSP because of the price. People seem to think that they should only be paying $150 or less for a handheld not $250, the same is happening with the PS3, because it is double the price of the competitors it is alienating potential buyers apart from the hardcore.
First and foremost the price is the killer. Just like the PS2, the GBA would still be selling loads especially if it was lowered to a ridiculously low price like $50 or so....just like the PS2 that can be picked up for half that of a Wii.
By bringing out a really cheap system is winning half the war straight off.
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)