I think history is going to be kind to these Spurs. Duncan obviously will be remembered as an all-time great. Ginobili's advanced stats, Olympic exploits and winning on every level will always keep him in the conversation as being one of the best and most dynamic shooting guards ever. If Parker keeps it up, it's going to be really difficult to look at his career achievements and not be really impressed. He's unique in that he reached a high level early in his career and then not only sustained it but continuously improved. Most point guards peak early ( , players like Chris Paul, Deron Williams and Derrick Rose may have already peaked and they are all younger than TP). Speedy point guards usually fall off a cliff late in their 20s (look how Devin Harris looks like a washed up scrub already ... and players like Kevin Johnson and Terrell Brandon were basically done at 30). If Parker keeps it up for even this year and next year, his resume is going to look great.
And then we have to factor in that most "great" point guards are unable to win championships. PG-led teams almost never win so Parker's championships are going to stack up well against others.