I find it hard because it is relatively expensive. Apple barely had any option on MBA, regarding that. I think Apple will keep the HDDs on the MBPs.
What I can see, however, is the removal of the ODD. With Mac Store and the OS X installable via Flash Drive (it's on the MBA page), the uses of the ODD will be reduced immensly!! That'd allow space for a dedicated graphics, more battery... possibly an alternative solution to Sandy Bridge on the MBP 13''!