...The only way to tackle this is to have a very open and honest culture around mental problems. Airlines need to be very clear that it is a disease like any other and that time and resources will be put into you rehabilitation just like any other and only when all avenues of recovery are exhausted you may lose you medical certificate but be eligible for normal loss of licence provisions...
Bravo to your whole post!
I fear the reality will be a different one, more along the lines of more regular and rigorous checking, colleague reporting, blaming and terminating, thus creating an even larger culture of fear and suppression, with predictable consequences.
Unfortunately the industry has suffered from a good amount of neglect and lack of oversight on behalf of the regulators and authorities. Practices as you mention flourish in a deregulated environment where profit is all that matters and safety an afterthought. Difficult to reverse this trend and broadly establish positive, open and trust based cultures now.
Ideally, airlines would do all in their power to get the best and most promising candidates (and not the ones with the biggest wallets), and hiring them would make them assume a large responsibility for the supervision and development of each flight crew member. As with management positions in good companies, flight crews should be eligible to good working conditions, and in case things aren't working out to the satisfaction of the employer (for whatever reason except willful neglect and criminal conduct), generous serverance packages/loss of license deals should be the norm.
But perhaps I'm dreaming.