WI Phillip of Swabia not assassinated in 1208

Hohenstaufens-Capetians are allies against the Plantagenets-Welfs. John Lackland gets excommunicated in 1209 and St. Louis gets elected.

OTOH, the Capetians might be LESS comfortable with the Hohenstaufens if Phil starts consolidating his rule in Germany (which he seemed to be doing).
Does anybody here know anything (beyond Wikipedia) about the German Throne Dispute, and how this assassination changed the fate of the Holy Roman Empire and of Medieval Europe as a whole?
It led to Frederick II of Sicily getting the German Throne, which united Sicily and Germany in a personal Union, which theoretically surrounded the Papal States.

If Philip of Swabia retains the German throne and had male heirs, then the German and Sicilian thrones remain separate.