I cant see Ford killing the RS off forever, more than likely they will go with promoting the ST for a while, maybe another year or so, then bring out a new killer RS. Who knows, perhaps the new mondeo in 2007? (I doubt it though, probably be an ST version of that only).
Im only guessing, but It would be nice to let the ST versions run for a while then bring out a stonking new RS Focus or Fiesta.
Rich