The only way I see this is if the Lakers can figure out a way to get George, James, and some other star (like Westbrook). That team would have a realistic shot with 3 stars and James isn't leaving Cleveland to go to a team less likely to even make the Finals.
If James goes the young player route, I maintain the Sixers are far more likely, especially if Embiid can stay relatively healthy this year and Simmons and Fultz look like they might hit their potential. That would be a nearly identical situation to Cleveland when he went back, except the Sixers have more young pieces and enough cap room to flat out sign him without dumping anyone. And if the Sixers do dump some players, they could theoretically acquire James and someone else. Imagine James and Westbrook with Embiid, Simmons, and Fultz, with Saric, Holmes, and Covington on the bench (not to mention they might also have at least one more lottery pick in the next draft). That team would be set up to win for a decade.
Do they have the cap space for PG3 and Lebron?
The Lakers can pretty easily make room for Lebron and PG13. The Sixers are a bit trickier, but I believe they can get there by making a few salary dumps and by not extending Embiid now or renegotiating and extending Covington (which is why I don't think either of those happens). Well they could extend Embiid now if he takes less than 18.3 million that 1st year which is his cap hold. I just don't see him extending for less than that. Covington's cap hold is only 1.5 million.
So with that caveat, the Sixers have 40 million or so on the books for 18/19 which includes Fultz, Korkmaz, and Bayless as the only guarantees with the rest coming from team options on rookie deals for Simmons, Okafor, Saric, Anderson, Holmes, McConnell, and Luawawu-Cabarrot. So that is 10 players (if they keep all of them). You then add in Embiid and Covington and that puts the Sixers at right around 60 million with 12 players (so no other cap holds needed). So that easily yields one max contract, but the 2nd is more problematic. However, if they can dump Bayless' 8.5 million and they don't pick up guys like Okafor (6.3) and Anderson (2.5), then they would get awfully close to having room for 2 max contracts. They could then re-sign Embiid and Covington (and as said if Embiid signs for less than his 18.3 million cap hold, they could re-sign him first and save more money off the cap).
From a 2 max perspective they'd actually be better off transferring the LAL pick to Boston next year, because if they keep it when added to their own pick that hurts their potential cap space, though does add a couple of more roster spots making unloading someone like Okafor easier. They also would be able to trade some of those players for that 2nd max contract if said player forced his way out. OKC might be ok taking on Okafor, Anderson, etc. if they were going to lose George anyway.