This is a cool idea. If you add the ability to be notified for a breach of SLAs, you might be able to turn this into something people would pay money for.
I got shafted for $500 on a car rental I wasn't given and support refused to talk to me. Definitely not interested. I honestly just hope you go out of business at this point.
I've had a logitec keyboard with a small display on it and the software was terrible. There were enough people writing things that interact with it, so it was useless most of the time.
I think the software is what will make or break this concept. It needs to be hackable. It should probably define a standard generic interface. People need to be able to integrate it into various applications in complex ways. It'll be weird to have multiple applications that try to change the layout in their own ways, so you need a daemon that makes the final decision and you need a simple, intuitive but powerful way to control this behaviour. If not done correctly, it'll be a nightmare and/or completely useless.
For my use case this is less secure because I keep my computers clean of malware, and my hard drives encrypted. I don't reuse passwords and I don't log into my account from devices I don't own. My phone, on the other hand is easy to steal. Anyone who has my sim card can use it to log in. I've also heard it's trivial to use social engineering to redirect a phone number with some carriers. Also, I often don't have signal in buildings, so that makes this option useless.
For other people the SMS option might be better. They let you choose which one you want to use. I guess we'll hear about the results of this experiment later on.