They'd be wise to learn from history: There are many people willing do your job for cheaper, most of them in other countries working for smaller wages.
Then why didn't all start ups outsource all their IT jobs to India for instance already? They are considerably cheaper than US software engineers.
I mean what stopped all these IT businesses to do that yesterday? I know more instances of businesses that tried to outsource their IT overseas only to go back on that decision, than successful IT outsourcing stories.
Seems like they did learn from history. Unions are they only thing that have proven consistently, across the world, to protect wages, rights, and give workers a say in their workplaces.