Whatever your views in this, its clear that if Audi does indeed keep with their "one RS at a time" philosophy, we are talking about waiting at least for the RS6 and RS5 to run their course before the next RS4. This means we may never even see a B8 RS4 - it could have to wait for the "B9" platform instead.
Now of course that RS5 is probably the more logical comparison to the E92 M3 anyway. The RS4 is a sedan, and since there will be an E90 M3, those two are more directly comparable. But still, even the RS5 will have to wait until after the RS6. That's means its probably a good 3 years away, if not more.
Bottom line, come MY2009, there will be no RS4/RS5 on the lot to compare to the M3. I guess that means, for the folks shopping for a new car, the M3 gets the nod. I mean you can't really consider purchasing a car that you can no longer find at your dealership.