What does this look like? Progressive taxes go up, better safety nets, those are straightforward. What does a solid middle class look like when all the cheap labor manufacturing comes back to automation (~8% of US jobs are manufacturing).
The US service sector is almost 80% of the economy. We are walking into perpetual labor shortages due to structural demographics. So perhaps we don’t need “good, union jobs” and instead need to make sure people are paid enough to live comfortable lives, regardless of job (services, manufacturing, whatever). Some combination of universal healthcare (squeeze out the profit potential, cram down non care costs), public housing (see how Austria does it) to prevent investor capture, increasing the minimum wage further faster, etc.