You can't please everyone all the time, and while Sony has patched things up with Immersion and announced they were "open" to changing the Sixaxis in the future, they're not touching the PSP. A theory had surfaced a ways back, a theory had had the PSP seeing a DS-lite-like design remake. However, Sony denied any such changes at the GDC, and said the PSP is staying the same.
One Sony rep stated that the PSP would soon "reach its promise," which is probably an allusion to the upcoming full connectivity with the PS3. In other words, perhaps you'll be downloading movies directly to your PSP at some point, although it's a firmware update that is still a ways off. However, updates are imminent, so cross your fingers the big ones show up in the next few months.
But either way, the PSP will not – we repeat, will not – be undergoing a redesign process. So you can lay the aforementioned theory to rest.