In an 82 game season, the East has never failed to produce a 50 win team, though it did come close a couple of times (most recently in '03 when the Pistons led the conference with 50 wins). Has happened twice in the West, but that was way back in the 70's ('70 and '75).
I know LeBron's teams have kinda been trending down during the regular season, 54, 53, 51 wins in 3 of the last 4 years. Even with 51 wins last year, and all the turmoil in Cleveland, I have a hard time picturing a LeBron team failing to break 50 (assuming he plays at least 70 games).