What I would like to see is software U2F keys that browsers sync for you. I'm sure this would upset some people but I don't think the average user has the abili

What I would like to see is software U2F keys that browsers sync for you. I'm sure this would upset some people but I don't think the average user has the ability to understand and maintain a set of security keys. Furthermore you have to maintain the keys separately for each site. This means that I only use 2fa for a small number of valuable sites, because the pain of rotating the credentials is huge. However most people I know have browser sync set up. They are using it for passwords. It would be great if it could manage a security token for them and allow authentication to websites without risk of leak.