I would quit tomorrow if top rate down the road wasn't there. The career isn't worth anything less than top rate to me. In fact the healthcare and pension are what really makes it worth it.
Progression is nothing more than an investment in my eyes. Just because fedex guys, and Amazon people are willing to work for pennies doesn't mean I'm going to. Cut wages, raise the burden on the employee for Healthcare costs, cut the pension. That's fine.
I can go work construction and make nearly 50/HR operating heavy equipment and low 40's/HR to labor via prevailing wage. Worse work conditions and a lot of traveling which I didn't care for but jeeze there's money to be made if you have a good head on your shoulders and aren't afraid to get your hands dirty...
I would think in the end these are the type of people that eventually grind it out at UPS and make it in the long run. These same people will say to hell with it if things go backwards because they are the type that can always find decent work anywhere because sharp hard workers are hard to find today.
The company my dad works for went two tier wages a decade back and it's been a nightmare. The age old saying "you get what you pay for" comes to mind. They in fact just recently substantially raised wages/bennies for the second tier because they are dying for qualified people that will stick around. The current meter reader who makes 11/HR asked my dad what the job paid when he started 32 years ago. The answer. 13/HR.
Until things swing back to companies investing in their workforce instead of shareholders, I'm afraid things will continue to get worse for everyone.