Note that
1−a+bca−bc=1−b−c+bc2bc=(1−b)(1−c)2bc
The inequality is equivalent to
(1−b)(1−c)2bc+(1−c)(1−a)2ca+(1−a)(1−b)2ab≥23.
Manipulation yields the equivalent
4(bc+ca+ab−3abc)≥3(bc+ca+ab+1−a−b−c−abc).
This simplifies to ab+bc+ca≥9abc or
a1+b1+c1≥9.
This is a consequence of the harmonic-arithmetic means inequality.