[HerenIstarion]

Saruman's fate re:

For he will lose the best part of the strength that was native to him in his beginning, and all that was made or begun with that power will crumble, and he will be maimed for ever, becoming a mere spirit of malice that gnaws itself in the shadows, but cannot again grow or take shape. And so a great evil of this world will be removed.

The quote above concerns Sauron (in case the Ring is destroyed), but I can't see reasons why should it not apply to Saruman as well. Outward signs are similar after all:

Saruman

To the dismay of those that stood by, 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 sigh dissolved into nothing.

Sauron

And as the Captains gazed south to the Land of Mordor, it seemed to them that, black against the pall of cloud, there rose a huge shape of shadow, impenetrable, lightning-crowned, filling all the sky. Enormous it reared above the world, and stretched out towards them a vast threatening hand, terrible but impotent: for even as it leaned over them, a great wind took it, and it was all blown away, and passed; and then a hush fell.

Void re: it may be hell in the sense of not existence of hell - it is opposite of Being in that respect. But in not the hell in the sense of a place. In fact, Void is not a place at all, it's nothing

cheers