Well, if you want hardware-accelerated decoding, you need new hardware. That seems reasonable?
Software encoder/decoder implementations will also be a thing in the interim, until the hardware is ready.
Software encoder/decoder implementations will also be a thing in the interim, until the hardware is ready.
Even if AV1 and VP9 share structurally similar components, no VP9 decoder is going to work out of the box. It may mean that people who produce AV1-capable encoding/decoding hardware have a better starting point, though (provided they had VP9 hardware, beforehand)