I don't think we'll see 50/50 coaching split based purely on merit. Women aren't/won't be integrated into men's teams as players beyond like 10 years old. So men will have an obvious advantage of the ins and outs of men's basketball for many more years than most women. This should naturally result in a higher percentage of men coaching men's basketball. If we were to see otherwise, it would be either anomalous and temporary or based on something other than merit.
I don't think you can correct this at lower levels either. Because you won't want to steal girls away from playing careers (on women's teams) just so they can have opportunities to coach men's teams. Naturally, you'll want them to fulfill their playing careers before moving on to coaching. By then, they are well behind their male age-group peers in terms of men's basketball experience. As much potential as a female may have at that stage, she'd have to put in more time in order to catch up in her career, if it's based on merit. The prodigy coaches would still break through. But not enough to make it 50/50.
Perhaps, you could be more selective for men who coach women's teams because the inverse should be true, too. Women should have more experience and better resumes at earlier ages than men who transition from playing to coaching.