I dunno, I just don't buy it.
Lebron might very well be willing to take a significant pay cut, but I struggle to see Melo, Wade and Bosh all taking the sizeable cuts necessary to fit their salaries under the soft cap. Those guys don't make anywhere near the amount of money Lebron makes off the court.
This soft cap this year is due to be approx. $61m or so, so that means they'd have to each take salaries south of $14m each, when you account for Halsem's player option, and the various cap holds for their draft picks and empty roster slots. Even if Riley can convince Halsem to decline his player option (doubt it), I just can't imagine a scenario where Melo, Wade and Bosh all take such low salaries.
Unless, of course, Lebron plans on playing for the veteran's minimum.