Saruman's death

[mormegil]

…about the body of Saruman a grey mist gathered, and rising slowly to a great height like smoke from a fire, as a pale shrouded figure it loomed over the Hill. For a moment it wavered, looking to the West; but out of the West came a cold wind, and it bent away, and with a cold sigh dissolved into nothing […] long years of death were suddenly revealed in [the body], and it shrank, and the shriveled face became rags of skin upon a hideous skull.

Read the above section from Return of the King and I want to know what other think happened to Saruman after his death, did he simply cease to exist or does his Fea continue to exist but forever changed? It's obvious he was not admitted into the west.