Yes I would expect that since it's a LOT more than Netflix and it's just sports really. Google would not be hurting supporting this niche of users. My opinion of course.
They do have a large select of sports (which is a plus for some), but there are a lot more channels than just that. Everyone watches different things, of course. The only channel I miss is the History channel.
More importantly ... if I download this app ... does it permanently replace the standard Youtube AppleTV 4 app that shipped and is currently installed on my AppleTV?
It's a separate app.