we'll probably have Sempron options on s939 once A64/X2/FX support is dropped from it. Perhaps even Turion options, assuming AMD doesn't develop a specific socket for a unique mobile only oriented part, true competition for the Pentium M. However I doubt that woud happen. I'd assume we'd see a mobile dual core chip on the 939 socket to compete with a dual core Pentium M, but you never know, perhaps AMD will make great strides in sales and have the gains needed to develop a unique mobile platform which would mean less gold overclocking mobile chips on the desktop front.
Although I agree, I doubt we'd see much past 2.6-2.8GHz X2 and 3.0GHz FX if AMD decides to even bother with it - breaking the 3GHz barrier seems less and less important now that dualcore is here to stay...until tripple or quad or morecore or whatever is coming next that is 😉