MLB players routinely have contracts for multiple season, so I'm not sure what you're talking about here. How many salaried engineers in the US do you think have multi-year contracts compared to "at-will" employment?

Also, I'd argue that establishing a union when a profession has relatively high social standing and pay if it seems likely that things will get worse is exactly the mechanism for fighting back against that decline. It's a lot harder to get management to agree to your terms if you've already lost most of your influence.