You probably should not wait: it will be 2 years of testing according to the announcement, and if you’re doing a retrofit most the cost of installation will be installing the transfer lines inside, mounting the unit, etc (opening walls and closing them back up). Transferring from an old outdoor unit to a new one should be a fraction of the original install cost (basically just the new unit cost plus the cost of hooking it up).
But, if you’re willing to wait or pay extra for the efficiency gains, you might be even better off getting set up with a ground source heat pump now. The install cost is more up front, but because ground temperature is higher than air temperature in winter and lower than air temperature in summer, the differential you need to pump in or out is a lot less, and therefore much more efficient. I don’t think any air to air heat pump in the next 20 years will be as efficient as a ground to air system you could install now. The air to air systems just have lower up front install costs.
In the US, there is still a 30% federal tax credit for ground source heat pumps as well. Many of the other energy credits have sunset (such as solar, I think)
But, if you’re willing to wait or pay extra for the efficiency gains, you might be even better off getting set up with a ground source heat pump now. The install cost is more up front, but because ground temperature is higher than air temperature in winter and lower than air temperature in summer, the differential you need to pump in or out is a lot less, and therefore much more efficient. I don’t think any air to air heat pump in the next 20 years will be as efficient as a ground to air system you could install now. The air to air systems just have lower up front install costs.