If labor unions wish to survive into the global glut of labor in the early 21st century they should change their base philosophy.
The idea behind unions is that workers should be protected no matter what, that business owners are adversaries who will drain as much profit potential as possible from labor, they will take advantage of labor. But governments are not eager any longer to buy into this proposition, and without the support of governments, or labor scarcity, unions lose much of their bargaining power. Location of production operations is too fluid in the global economy.
So what unions should do to really protect their workers is market their workers. Market them as the group who will take the fewest sick days, market them as the best trained workforce, market them as the most safety concious workforce, without cutting wage expectations unions can market the profit making potential of a top of the line workforce. Something more along the lines of what guilds used to be. So yes maybe you want a non union workforce, but if you do you want to be saddled the extra costs involved in carrying such a workforce.
If unions can do this they can insure that they can provide high standards of living for their members. This is especially true if they can market their workforces internationally. And foreign governments rather than view unions as a destabalizing influence could come to view them as the best way to move their economies forward.