Toward the end of his presentation today, Sony Computer Entertainment America president Kaz Hirai revealed that Sony is considering an alternative to the PlayStation 2 hard drive.
Following a brief speech about how Sony takes user responses seriously, Hirai mentions several feedback-inspired ideas the company is currently considering. Some were minor, such as allowing skilled gamers to sell in-game items (the example he gave was a tricked-out car in Gran Turismo) for real money to "rich players who have less time."
However, Hirai also mentioned Sony is considering a "non-HDD contingent solution" for the console--in other words, a replacement for the HDD. However, he didn't elaborate on what the alternative would be or when we might see it.