I didnt mean "permanent top 10" , it is very hard to achieve, only superstars can do it year after year after year. Big Boys Club I meant more being almost always seeded in slams and to be top 10 sometimes, then drop out of it, but not very far. Like Almagro or Verdasco.If they are doing very well, they are in top 10. If they are in slump, they drop out of 10, but still remain in top 32,in the elite group of slam seeds.
OK didn't know the definition of the "big boys club"
but what you say I think he can do it.
After all, Isner has been in that club for 3 years, and Karlovic managed to get there for a while with not much beside his serve.
With such a serve "you can travel comfortably" if you have some bases besides. And some bases he has. And he's only 22 years old in 2 weeks.