If I sign on w/ Facebook/Google, they still have to authenticate me with a password.
If I have a token emailed to me, I still have to access my email with a password.
If I have a token sent to me via text, I may still have to unlock my phone with a password -- and I have to have the phone on me.
There are only three ways, that I can think of, to authenticate someone:
1) a password (or some other secret)
2) a token stored as a cookie or some other file on your computer/device
3) a token sent to/stored on a personal device.
Most products already implement #1 and #2. They will look for a token, and if not present, will prompt for a password. In the case of third-party authentication (Facebook/Google/email), this authentication is still done via a token, and if not present, will prompt for password -- it's basically pass-through authentication. I don't think anything can be done to revolutionize either of these.
That really only leaves us with #3. Texting a token to a phone works and prevents having to remember a password (or use an unsafe password), but it's still inconvenient.
Has someone tried creating another device that serves as a "key" and connects to your device via USB/bluetooth that can be used for authentication purposes?
This is about the only thing I can think of that would be a step in the right direction, but even then, there are probably still a handful of reasons why that would be problematic.