I know a couple people who have been flying as a hobby for years and even done a significant amount of flight instructing to help pay for it. They have enough hours to fly for a regional, but they have another reasonable job and not much desire to spend nights away from their family.
I'm sure, say, $200K/yr will be well more than enough to get them off the sidelines. There certainly are enough of them to cover the current shortage a few times over.
We're talking a significant increase in air ticket prices at those pay rates though.
In the long term, airlines are just going to have to suck it up and pay for the training, probably through loans that are forgiven after a certain number of years working, as well as paying a reasonable salary for all pilots.