A thing to note. All those Clone Troopers are actually only maybe 27 years old at the time of Rebels. Yet they look like badass Santa. Any remaining Clone Wars era trooper in the Empire would also look like that (save with regulation hair and a newer uniform).
I can only image the Empire keeping the clones that were put into motion during or before the Clone Wars as they would have been paid for. The making of new clones would have ended at war's end I think, or very shortly into the reign of Palpatine. as Emperor. These last clones, the ones born during the war (using the method on Kamino rather than any faster methods) would be older than the clones we saw in the war (14 or 15 years old at the youngest) and still be viable troopers with bodies around 30 year old., just a little older than Rex or Cody looked during the War. But they would only be viable like that for maybe 5 to 10 more years. At least as far as he Empire would be concerned with them being front line troops or officers. Means the last viable Clone Troopers would be aging out just after Endor. They looks viable as troopers from age 8 or 9 to age 20, maybe 25. Some might be well as officers or the old Chiefs and the like up until 30 or at the latest 35 I would think. After that they'll probably start to get frail and died of old age around 45 to 55. Not sure what the human life expectancy is in Star Wars without the actual wars going on.
