I suspect due to the Vita's high price, the PSP/PSPgo will stick around at least another couple of years.
Obviously games like Uncharted: Golden Abyss will not run on the PSP (the Vita's got a quad-core processor), but that's not to say the PSP won't get a toned-down version of it. Established PSP franchises will probably still be produced for the system, but many developers will probably focus mainly on PS3 and Vita titles.
I'm happy to see that Vita games will retain the PSP's $40 price point for new release games.
That alone may be the deciding factor in my day 1 purchase of a PS Vita.