It's worth reading in full, even if they're not the first ones to ask this question. In a nutshell, the theory is that attacking public teachers is a vehicle for attacking, and dismantling, public schools—to pave the way to privatization. It's the Reagan-age-old argument that market competition is the only way to fix a system the public has been convinced is broken.
Here's a glimpse at some of the loopholes in the argument for firing "bad teachers":
The attacks on teachers are phrased in terms of "closing the achievement gap." In fact, the first paragraph of Newsweek's "Why We Can't Get Rid of Failing Teachers" story concludes: "Within the United States, the achievement gap between white students and poor and minority students stubbornly persists—and as the population of disadvantaged students grows, overall scores continue to sag."...
if closing the achievement gap were the goal, we would see demands for adequate, equitable resources and funding for every student in every school—demands, for example, for quality early childhood education programs, full-time librarians, robust arts and physical education programs, mandated caps on class size, and enough time for teachers to prepare and collaborate. We would also see a renewed commitment to affirmative action in university admissions; a drive to recruit and nurture teachers of color; a commitment to ensure that students come to school ready to learn because their families have housing, food, medical care, and jobs; and an end to zero tolerance discipline policies that criminalize youth.
"Teachers can defend themselves from this hailstorm of criticism only if they make common cause with everyone who has a stake in defending—and transforming—public schools," write the magazine's editors, adding that a coalition of teachers and parents working together is crucial.
I would add Sir Ted Robinson's point that part of the problem with our education system is that it has focused on teaching kids to become good workers, rather than creative thinkers.
And while the Rethinking Schools editorial was not focused on environmental issues, I will venture to raise them here. School gardens have been proven to have real value for kids and provides lessons that a classroom never could, and environmental literacy—something that students want—is being increasingly recognized as an important part of education.
Attacks on public schools and teachers could be a path to privatization—not that privatization isn't already happening—but the editorial authors still find hope, as long as all players work as a team. To conclude with their well-written thoughts:
The survival of public education depends on our ability to grasp these larger truths. For all their faults, public schools are at the center of building democracy, community by community, from the ground up. It's going to take all of us working together to save them and turn them into institutions that promote democracy and empower youth—all our youth.