This has all the trappings of something that sounds like a good idea in theory but will most likely falter in the marketplace.

Considering how cheap you can get a laptop or tablet these days with a much faster CPU, more memory etc than a smartphone.

Also considering that it's going to be a pain in the ass to go around hooking/unhooking your phone from every device that you want to use. The software for each device is likely to need to be different too or provide a farily sub-par experience, leading to a lot of confusion.

Also , if you lose your phone you're not just losing your phone but also the brains behind all your other devices.