SGA is already the third greatest point guard of all-time.
SGA already has an extremely strong argument for 3rd all-time in his position. What other point guards have two MVPs, a finals MVP, and a ring? Magic and Curry, and now SGA once he wins MVP. You can argue names like Isiah Thomas (No MVPs), Steve Nash (No rings, No FMVP, Didn't even make Finals), Oscar Robertson (1 MVP), Chris Paul (No MVPs, No rings, no FMVPs), Stockton (No MVPs, No rings, No FMVPs).
You can argue longevity, but I would say that Shai already has one of the greatest four year peaks for ANY player in history. GP: 71.8, MIN: 34.2, PTS: 31.3, FG%: 52.9, 3PT%: 36.5, FT%: 88.9, REB: 4.9, AST: 6.2, STL: 1.7, BLK: 0.9, TO: 2.4. So is four MVP level seasons really worse than 10 seasons being 10-15 level guy in the league?