I just don't see how that would be remotely possible. Lebron is a far superior physical specimen and athlete with the same level of skill as MJ. MJ went about 210 while Lebron has 20 or more pounds on him and its all muscle. He could push MJ into the bleachers just by backing down. He also has 3 inches plus more in wingspan on him. Constant debates like this are akin to the debates about who was better Jim Brown or Barry Sanders. If Jim Brown ran against the same caliber defenses and athletes that Barry did JB would've had a tough time cracking 1,000 yards. All the love and memories of JB in the world won't change the fact that that athletes he and his fellow pros were at the time were EXPONENTIALLY inferior to what Barry was and played against and to compare JB against someone like Adrian Peterson seems almost silly. Sure JB was to his generation what BS and AP were/are, but sorry JB would've been average in the BS or AP league. Similar to what MJ would be now in the league. When MJ came up it was freakish to have his combo of size and athleticism which helped him dominate the game...at that time. (I would also argue the entire league was down a bit because Magic and Bird and their teams were in their twilights) Now its almost par for the course and nearly every team has someone who's a freakish athlete that plays the 2 guard or 3 swing that goes btwn 6'6-6'9. Heck Dirk is 7 foot and plays the 3 most of the time. Okay, sure MJ could probably still score today, but you can't tell me he could begin to d up kevin Durant, Kobe, or Lebron, all of which have significant size advantages and every bit as much athleticism, if not more.
Furthermore, no NBA star has ever got the star treatment as much as MJ did, he nearly created and expanded it. He got away with murder and got to shoot 20 freethrows per night. Anyway, this entire debate almost seems silly to me, MJ was the greatest of his generation leave it at that. Players have gotten bigger and better since then, same thing that has happened in every sport.
Next up, let's compare Royce Gracie vs Matt Hughes, two diff generations of MMA fighters....oh wait they did go head to head and that was a severe beat-down.