[Inziladun]

I'd agree that Sauron and Saruman would likely have no power any longer to affect the physical world, though I do like Legate's idea of a select few 'sensitives' being able to see them from time to time.
If they happened to encounter one another in spirit form, I wonder how they would converse, with no physical bodies. Some sort of thought transference? Even if they had originally possessed that power as Maia, it doesn't seem they would still have had it in their lowly state.