However the small SRAM space and limited clock speed on the 8 bit AVRs does rule out many valid hobbyist level projects that really can't be performed on the existing arduino hardware.
Maybe I am lacking imagination, but how about some examples?
My fear is that too many begineers will choose a Due over a Uno based on their possible future requirements rather then picking the best board for their entry into this hobby.
Definitely, a lot of people tend to buy the latest and best, even if it isn't the right one.