Yeah I could imagine the AV1 codec sticking around for a very long while, even as a fallback for AV2. There's still hundreds of millions of people out there using old/cheap devices (especially in developing countries) where that battery drain from software decoding is a big problem, so AV2 would be nonviable.

Some of the early use of VP9 and AV1 was Netflix serving video to people in developing countries. Their metered bandwidth was more of a bottleneck than the CPU playback.