Cool points for the developers
A good evolution given where the CPU market seems to be heading and "cool points" for the developers for pulling this off.
However, with a cupboard full of different PI versions since they first came out and several stuck with Velcro to different things around the house, I can't see a need to virtualise them as its often the form factor, options for physical placement and access to the various ports that is most important.
If the memory capacity keeps increasing, then I might change my mind, but I'd expect that most would probably want to containerise rather than virtualise and docker has been on them for a long time now. IO rates to the SD card will also be a problem, so I guess definitely a Pi4 only solution where USB3 exits
There are a couple of areas where I expect this will be extended in the coming months.
1. A virtualised ARM based mobile phone, one virtual one for the way through the airport and one the real one for when you get there.
2. Some form of malware / rootkit that uses the new virtualisation as this always seems to follow such evolutions.