Basically what they would do is offer scholarships or funding assistance for those who commit to working for them. They would not want to open their own flight schools or incur other long-term obligations.

If they suddenly didn't need the pilots, they would not be able to get their funding back, but they would not offer any additional funding.

This would also have the advantage of giving airlines the opportunity to screen people for non-pilot attributes (HR stuff like education, grades, people skills, etc) and getting the best potential candidates "on the hook" early on.

There are all sorts of ways they could financially entice student pilots while still keeping them at arms length and ready for quick disposal if necessary. The LAST thing they would want to do is put an ab initio pilot on their seniority list or raise pilot payscales...those are much more permanent obligations.

Right now the problem is attracting new-hires...if it gets bad enough that can't retain enough experienced pilots to serve as CA's then they will HAVE to raise payscales. But for now it's cheaper to give an entry-level candidate a $10, 20, or 30K one-time scholarship than it is to give CA's a $20K raise...that will recurr every year.