Actually there is a chance Andy will be considered a great.
The 'big four' idea has resonated internationally. It is likely to be fondly remembered, and although Andy is only a 'prince' next to three Kings he is still an iconic player.
It tends to be hardcore fans who slam count closely - the more casual masses remember big names and big clashes - the names that kept appearing in finals and semis etc.
Yeah I agree that there is a chance there for both Stan and Andy to be considered in terms of being great...just that as things stand they won't imo. Both considered very good players but not in same class as Fed or Nadal yet. Djoko still struggles to be considered a great...and his haul is far superior.
Also, I don't see Andy having as long a career at the top as Fed. Andy's tennis has som much reliance on court speed that Id say if he hasn't added to his slams in the next 2 yrs that'll be that.