PSP is about six years on market and continue to selling not bad right now.
It sold 50+ million consoles.
It made 30+ million seller titles.
It made a fanbase too.
So, PSP is already successful console. But PSP's life time comes nearer to the end.
I sure, Sony understand this. No doubt, they are developing the next portable console, I think it will be announced on E3.
PSP2 will have all chances to be successful too, but Sony exactly need to take into account mistakes of the first console, piracy first of all. =)