I think Canon should create long time trust among 'their' photographers who, (just for an example) want to invest in the cropped sensor line, but who are not sure if there will ever come quality L glass available.
L-glass already fits the cropped sensor line-up. L-glass primarily distinguishes itself by build-quality and weather-sealing. It shares these traits with bodies found in the Pro series only, not with any of the cropped-sensor bodies.
So you will likely not see any L-versions EF-S. However, this doesn't mean that some of the (future) EF-S lenses will never out-perform L-glass. On the contrary, on cropped sensor bodies under specific circumstances EF-S may be indistinguishable if not better than L-glass. The 10-22 may already be an example of this.
I believe that Canon have 3 levels of SLRs:
The first level is the pro series line-up which will be extended over time and which is indicated by the single digit naming convention. A lower number means more features, more rugged. Price is not a driver, quality is.
The second level are the advanced series indicated by the double digit naming. You are not likely to see a weather sealed camera in this line-up. These camera's represent a compromise between price and quality.
The third level is the basic SLR series with triple digit naming convention. Price is the driver (meaning quality is always compromised for lower cost).
And obviously they have a fixed lens (P&S) line-up.
It is clear that the Pro series bodies will all be FF eventually. IMO the next high-speed 1 version will already be FF and we will first see a 12MP FF high-speed 1-series body separately, before we see a fully integrated single 1 body. It would be senseless to build a '9D' whatever with 1.6 crop, as it would merely be competing with the level 2 offerings.
It is not quite clear to me whether level 2&3 will use a different naming convention as in higher numbers means more features and/or whether we will see a 15D as an upgraded 10D just as the 350 is an upgraded 300, or even a 10DmkII.
So a Pro who needs dependable equipment in rugged situations can make an educated selection of lenses and body. For advanced and wedding-jockeys it is not a question either; level 2 will eat both EF-S as well as L-glass, and for the very wide angle on that level, the 10-22 already serves the purposes quite beautifully.
I don't think cameras in level 1 and 2 are remotely meant for or based on swerving consumers. And even in level 3 I believe that the investment is high enough for a lot of consumers to make a longer term commitment. The "switchers" will likely find themselves in the level2&3 which is 1.6 crop so that doesn't represent a "strategic" investment on the consumer's side either.
Of course, I don't know for sure whether this actually is Canon's "strategy" but at least it doesn't seem to be entirely without pattern.
btw. Is your question/concern perhaps triggered by the 5D rumors?