He mentions the impact of globalization, but I think that it's a much bigger deal than he makes of it. For work that can easily be offshored (manufacturing, software dev, phone/online support, creative work, etc.) the obvious corporate response to unionization it to move shop. OTOH, for professions that
can't easily be offshored (medical, local services such as fire/police/utilities, education, etc.), many are still heavily unionized. Some of the unions are non-traditional - for instance, the AMA (American Medical Association) effectively serves a role as a Doctors' union even though they don't advertise themselves as such. They control training into the profession, they are the sole arbiter of who can practice the profession, and they generally work to suppress supply below the level of demand (and therefore drive up wages).
OTOH, software is already being offshored at a rapid pace (I really doubt whether I'd recommend that my children go into the profession), and I think that labor organization would only serve to accelerate that. Having said that, it probably could prevent some of the more egregious benefit erosions that plague our industry ("unlimited" vacation, anyone?) ... which would be nice while it lasted.