I heard that someone is working on getting things running again using HVM instead of PV mode, but I have no idea on the timeline. (Bcc'd him, so as not to put him on the spot if I got my rumor wrong)
I ended up switching to Google's GCE, and while I couldn't find any pre-built images, the process defined in
https://github.com/google/netbsd-gce worked pretty smoothly (though the lack of pre-built packages for netbsd-8 is annoying). Obviously that doesn't help if your production systems have AWS dependencies, but otherwise it seems like a good option.
You should probably expect that your prod systems *will* be forcibly rebooted at some point, but you can look in amazon's console to see when/if that will be. (There's a scheduled tasks section)
Eric