How good is he? Quite obviously world class, with the ultimate award to prove that.

How long to become a motorcycling 'great'? He already is. He has won the world championship. To stand out from the 'greats' (other world champions) I suppose he would have to win a greater than average number of championships, whatever that may be.

I think if he won three world championships you would have trouble arguing against him being one of the alltime greats.