Well, Sony will be stopping production on the PSPGo
as they have told AV Watch that they are concentrating on the NGP
and all remaining stock will be sold without any new ones made as reported by Kotaku
will keep on getting made so it's not like Sony's completely cutting off the PSP line with the impending release of the NGP. It's just like how Sony continues to make PlayStation 2's even though they have the PlayStation 3 out.
I know, in my circle at least, that the PSPGo wasn't popular at all with the changes Sony decide to make it on, such as the removal of the UMD drive. If Sony decides to do a nice price cut on the PSPGo, then it might be a good time to pick one up.