Since they haven't announced one already, I find it very unlikely. The UMPCs being released likely reduces the chance of a newer one being released. The only thing that Archos PMA has over the UMPCs is lesser cost, and even that advantage is likely to errode. So, releasing a new model now seems a poor decision, IMO.
That being said, a newer version with a higher resolution(640x480 or better) display for the same price as the orginal would be very tempting for me. More RAM and a better processor would make it very appealling, until $500 UMPCs come out anyway...