What it looks like is that Sony is implementing the PSP into their living room media hub strategy.
The PSP is kind of an odd gaming platform in that it is fairly unfocused as a gaming device.
A portion of people are primarily buying them to play PSP platform games (bought at retail), while a lot of others are just fooling around with the hardware itself through hacks (pirated softs) and to a tinier extent, home brew soft. What 99.99% of all users who say they're interested in the PSP for the homebrew community are really saying is that they just want to buy the hardware and get the games for nothing (just like the R4 user base).
What started to spark my interest in the platform was not necessarily the library of games available, which by any measure has been less than spectacular, but the connectivity functions with the PS3 platform.
Being able to purchase PSP softs on the PSN with the PS3 and then synch and upload to the PSP is a very nice capability. Being able to access all your media stored on a PS3 remotely makes it almost unlimited as a portable media device (barring the limited battery life). It's a good link to your personal living room entertainment not previously made available in a gaming device.
That's where the expansion lies, in the media and the platform that gives the user access, not necessarily in game cartridges and discs, which may well be obsolete in the next generation of handheld gaming devices. See game distro for the iPod/iPhone as the future distro system for PSP games as well, even if portable game media continues to be sold to appease retailers and the increasingly shrinking non-connected user.