It's not antitrust unless you're pushing install your own products and only pushing your products.

You knowblike Google do if you access any of there services not in chrome "download chrome here", "this site works best in chrome".

I really doubt this is the reason; for starters, the update of windows 10 i have now removed the option to disable Bing in the start menu, nor can I change the search provider. They're headed right back to where they used to be.

If they are going Chromium based, its only to ensure everyone uses their chromium browser