While the pair parted ways without ever getting a crack at the championship stage, it's fascinating to think what could have been if that split never happened—and not to just us awestruck fans, apparently.
The players themselves entertained those same what-if questions during the fourth episode of The Finish Line, Grantland's documentary series chronicling the final legs of Nash's basketball journey.
This installment, appropriately dubbed "Dinner With Dirk," includes a captivating exchange (starting at the 4:26 mark) where the two imagine life in a different NBA universe in which Nash never left Dallas.
"What do you think would have happened if I'd re-signed with the Mavs [in] 2004?" Nash asked.
"I'm not sure whatever would have happened," Nowitzki said. "I mean, obviously, people ask me that sometimes, and you think about it a little bit. But, you know, some people say, 'Hey, look, it was good for our careers to be apart, to grow without each other.'"
That growth included each player carving a spot inside the Naismith Memorial Basketball Hall of Fame.
Nash captured MVP honors in both 2004-05 and 2005-06. Nowitzki followed suit in 2006-07 then bolstered his resume with a championship and Finals MVP in 2011.
Clearly, the pair did well from themselves after the split. But that hasn't silenced those questions about what could have been.
"It would have been a hell of a time, though, I know that," Nowitzki said.
Nash, who's done practically everything in his 18-year career but capture a title, couldn't help but wonder if his jewelry collection wouldn't be empty had he stayed:
On the one hand, I feel like, we would've gone on and won a championship, because you did it without me. And I think at least in one of those two years I could have helped. So, part of me's like, 'Yeah, we both grew in different ways and better ways because we were apart,' but part me of thinks we would've won for sure.
It should be noted this conversation never happens without the foresight of then-Mavs coach Don Nelson. It was his vision that brought this pair together, swinging draft-day deals in 1998 for Nash (then a two-year veteran) from the Phoenix Suns and Nowitzki (a wide-eyed rookie) from the Milwaukee Bucks.
The pair needed some time to get its rhythm. Nash needed some more seasoning (he averaged 8.6 points and 4.9 assists in 1999-2000), and Nowitzki didn't exactly take the league by storm (he averaged 8.2 points and 3.4 rebounds as a rookie).
During their time together, though, the duo grew by leaps and bounds. And they brought the Mavericks along for the wild ride.
Dallas went just 19-31 in the lockout-shortened 1999-2000 season. By 2003, Nash, Nowitzki and Michael Finely lead the Mavericks to their second conference final appearance in franchise history.
However, it all came to a screeching halt in the summer of 2004. Nash, fresh off a 14.5-point, 8.8 assist campaign, inked a six-year, $68 million deal with the Phoenix Suns.
The rest, as they say, is history. Legend, in fact.
Both players left indelible marks at their positions, Nowitzki sparking the stretch-big trend that's now seen across the league and Nash paving the way for sharpshooting point guards like the Golden State Warriors' All-Star Stephen Curry.
It's hard to think there are any regrets. Then again, we can't look back at those days through the same lens as the ones who lived it.
"Who knows, maybe we would've won multiple [championships]," Nash said.
Maybe they could have, maybe they couldn't. The beauty of these what-if questions is that we'll never know the answers.
One thing we do know is that's a been an unforgettable ride for both:
It was a pleasure watching them join forces for those six scintillating seasons and a pleasure eavesdropping on their rousing what-could-have been conversation.
Watching them link up again in the Hall of Fame will be the perfect ending to these legendary tales.