OK here is some math.
Let's say Lebron averages only 22 pts per game starting right now and into the future (for whatever time frame he continues to play), ignoring the fact that right now he is averaging 26 ppg and has averaged better than 26 ppg every single year of his career except the first. And let's say he doesn't play the rest of this season, so we start with his career point total right now, which is 24145. Also, let's assume starting next season he only averaged 75 games played per season going forward.
So at 22 ppg and 75 games per season, how many years will it take him to catch the top 3 (Kareem, Malone, and Kobe)?
Kareem = 38387 pts, 8.6 years
Malone = 36928 pts, 7.7 years
Kobe = 32482 pts, 5.1 years
At his current career averages how long will it take?
Current averages = 27.5 ppg and 79 games per season (adjusting for current season and lock-out shortened season)
Kareem = 6.6 years
Malone = 5.9 years
Kobe = 3.8 years
This would make him 36-37 years old when he surpasses Kareem.
So what if he plays as long as the Mailman did (till he is 41, so 11 more years), and only plays 75 games per season and his averages drop to the afforementioned 22 ppg?
In that scenario he finishes his career with 42295 pts, 3908 pts ahead of Kareem.
What if he finishes his career exactly as Malone did (again excluding Malone's injury shortened last season), which is about 79 games played per season and 25 ppg over 11 years?
In that scenario he ends with 45870 pts for his career, a full 7483 ahead of Kareem. Close to 9k pts ahead of Malone.
So let's take a reasonable educated guess. Let's assume that he decides to retire at age 36, after chasing another ring or 2, maybe getting 1 in the process. And let's say he does drop off a bit his career averages, say 26 ppg and 77 games played per season (against his averages of over 27 ppg and 79 games per season). Where does he end up then?
In that scenario he ends up at 36157, ahead of Kobe and just shy of Malone.
Now remember, we excluded the rest of this season from our calculations to this point, so for this last more realistic scenario let's assume his current scoring rate and games played rate for the rest of this season, which is 26.4 ppg for the next 45 games, so 1188 more points, or a total of 37345, which is just ahead of Malone and just behind Kareem.
So at that point is it that big a stretch to think he might play one more season to take the top spot? He would only need 1043 pts to do it. So if we do stretch it to 7 more seasons he then passes Kareem by 960 pts.
All in all I would say, barring some major injury or a car accident or something, that it is fairly certain that Lebron gets at least to the 2nd spot, and highly likely he takes the top spot by the end of his career.