Your kool-aid mustache is showing...
IMHO the 737 type will remain in place at southwest as long as it is a desirable place to work. Funny how everybody expects a huge wave of hiring to solve all pilot inquietude. The truth is southwest was a joke 25 years ago. You only went there if a major wouldn't hire you. Legacy carriers have always used the cycle of bankruptcy as a tool to discharge debts from their bloated operations and when that cycle comes around the pilot pay piggy bank always bails out the bottom line.
Remember the one fact that illustrates the truth about our profession; the airlines as a whole have never made money. Not ever. Add up all of the balance sheets from all of the operators and it will always be a negative number. Feast while you can but save for a rainy day. True industry professionals are frugal and most are working on a second income (rental properties seem to be popular) to compensate for with scarce retirement savings or a plan that was taken from them just as they were winding up their careers. Flying is enjoyable and because you have the pilot bug you will always receive less than you should because there is always somebody else who will do your job for less.