Sock finished close to the top 20, so he'll probably have a few years in the top 20, and may even dip into the top 10, but won't be a regular there. I see his upside as a solid "third tier" player - the type of guy who is usually seeded at Slams (so top 32) and wins the occasional tournament, even an ATP 500 or two, but probably won't win a Masters and certainly not a Slam.
Fritz seems to be the American with the most upside. I think he'll at least be second tier (top 10, dark horse at Masters and Slams) and maybe even better.
If the rest, I don't see any likely elites but quite a few possible second and third tier players.