Maybe they just got it right with the G6? : )
Seems like they're pushing the S1/S2 pretty hard, they have 'em at Target now. It is a tough sell to sell a G7 or Pro2 for $100 or $200 less than an XT. For that kind of money, people expect SLR-like performance. Look at all the people on this list that were thoroughly dissapointed with their G6 until they started thinking of it as a fantastic point and shoot rather than a scaled-back SLR.
Canon are definitely not technology leaders, as we've discussed elsewhere, so maybe they're just giving the whiz-bang prosumer market up, it would make sense in the short run, but it's sad that they lack the foresight or initiative to try anything new when they have what I'd assume to be the market-leading camera at the moment.
Even so, I already got mine, so they can discontinue them at will.