That would suck. Why does Roberts have to totally recuse himself? Can't he participate in the jurisdiction question and then recuse himself from the rest?
The way the case is presented, it hits both the jurisdiction issue (Rasul & the resulting Congressional action re: juristictional statute); AND the merits of the case. Roberts ruled on the (Hamdan) case below, and therefore has clearly made up his mind as to which way the case should go. He can obtain the same outcome (no right to court review) by ruling as a matter of statutory jurisdiction.
I doubt the court is going to split 4-4. I think the plain language and intent of COngressional Action is to strip the court of jurisdiction in this class of cases, despite Senator Levin's protestation to the contrary. Believe it or not, I haven't read the case recently enough to have a sense of how a ruling on the merits might go.
As a matter of legal process, it's on the messy side, seeing as how parallel cases are underway in the Circuit Court.