A spokesperson told TechCrunch:
As of March 14 or later, Google will no longer sell Google Play for Education licenses. We're committed to providing schools with the best-in-class tools for the classroom, including Chromebooks, which are the #1 selling device in US K-12 education, and a strong and growing ecosystem of educational apps. We'll continue to support our Google Play for Education customers and the devices that they have purchased.
As you can see, the tech giant didn't explain why it's being axed, but its clear that the program is putting its focus on Chromebooks. The portal's death doesn't mean people will lose access to educational apps anyway: a 2015 Pew Research survey found Education to be the biggest sector in Google Play. It will just be harder for teachers to get students to download the content they need. Current subscribers don't need to worry about that right now, though. Big G will continue supporting them, and educators will be able to buy and push apps until their devices' end-of-life dates.