Developers will be able to take their Chrome extensions or Firefox add-ons and, with “just a few changes,” bring them to Microsoft Edge. Belfiore demoed a Reddit extension originally built for Chrome, running on Microsoft Edge.
I wondered why they'd bothered, but this might explain part of it. It's been ages since MS had a real go at EEE. Embrace other browsers' extensions, extend the standards so they no longer work with the original browsers and then extinguish them. I don't think it'll work this time though.