[quote=Asura]
Not all the clones are dead by 4BBY. The Clones of the 501st were almost entirely Clone Wars veterans and served as 'Vader's Fist' until his death and likely beyond. Many ARC troopers and Clone Commandos also escaped to Mandalore, where they lived into the ABY and eventually found a cure for their enhanced aging.
[/quote]

"Eventually" actually for many years they only found a stop gap while they continued to slowly die and a real cure was only found in 30-40ABY by Boba Fett who in being a clone was degenerating as he aged, while he missed out on the advanced ageing his body did begin to fail him.

In terms of Clones Vader had very few left years after the war actually.