I don't really think it is going to happen ...
The Wii is steadily climbing to 50% marketshare, and because of its larger userbase the Wii's software sales are really starting to take off. As the Wii consistently retains its hardware dominance it will become more and more important to third party publishers which will effectively prevent the PS3 from mounting a come-back.
In 2010/2011 the PS3 will have enough trouble attempting to convince third party publishers that the higher development expenses are justified given that the PS3's userbase will be so much smaller.