at a (previously) $20 price difference, why would they add a 3rd model?

I don't know what makes sense for Apple's supply chain and BoM, I'm just saying that the price for my home's worth of Apple TVs with the minimum functionality I use has gone up by over 50% since the previous-gen model and now sits at over $1,000 in local pricing.

That's the kind of pricing that makes me start to consider the Google 4K Streamer even if it's a UX downgrade - for $300 I get ethernet and Thread on every TV.