To be clear, you're saying they're just testing the waters with Chromium? Or with Fiber, which makes its own hardware STB/routers, or with this whole internet performance thing in general?
Chrome devices have 5 years of updates guaranteed. I have a cr-48 from 2010 which still gets updates (currently on -dev 56). How many times has there been a story on HN about RCEs unpatched for months or years in consumer routing gear? The fact that you purchased that hardware doesn't seem to be sufficient incentive based on the record. But when you have an incentive of a secure and performant internet, and also have the talent, infrastructure, and existing codebase to make something work and work well, you have economies of scope that make supporting it much easier and cheaper.