In the end AV1 will likely have about the same level of adoption as VP9 ... pretty much googe/youtube only. Allowing Google to monopolize video standards is not something that the hardware world is going to accept. HEVC already has near universal hardware support. Why bother with supporting AV1?
Google, Netflix, Amazon... so basically overwhelming majority of the video on the Internet. Left is broadcast video, where the HEVC support can be relegated to set-top boxes.
VP9 is the same generation as HEVC and performs about the same so the only reasons to favor one over the other would be financial and client support. For many providers this means 3 copies: VP9 for Android, HEVC for iOS/Mac, and H.264 for older devices.
AV1 is newer and should offer improvements over both previous generation codecs. Hardware support will be a significant factor but it’s looking as if in a few years you’ll have the option to use one better format on most modern devices.
Unlicensed content providers (this is the preferred politically correct term) have been doing HEVC UHD (4K) from day one.
Most TV shows and movies are available in HEVC at 720P and 1080P now but all it offers is smaller file sizes (not better quality) so most people don't care about it.
