Shoulda/coulda/woulda but doesn't really matter because Duncan was a better player than Lebron at every level of his prime.

Tim obviously couldn't care less about who gets what credit, "who's team it is." He's selflessly sacrificed at every segment of his legendary career to elevate guys like Manu, Tony, Kawhi, even to prop up an old David Robinson. The whole hypothetical about Lebron inside a Duncan/Pop/Spurs team doesn't mesh anyway. Lebron pouts and makes demands, he's passive aggressive and moody. He tries to send barbs to teammates and management through the media. That shit 100% doesn't fly in San Antonio, or under any room Pop or Tim are in.

Kyrie doesn't want to leave Cleveland to "be the man" somewhere. Otherwise he wouldn't want to go to Minnesota and San Antonio, where Towns & Kawhi are hands down 210% the men of their team (Pop & Thibs somewhat equally too). Kyrie just wants to get away from Lebron's antics and drama, which is why Lebron is the one who wouldn't fare well on a Duncan/Popovich team. The Spurs have always acquired great players, no doubt, but they acquire great people too. They value character, humility, sense of humor, work ethic, honesty.