I mean, this is basically something we have all wish for. This is basically the custom built desktop market coming to mobile phones.
It's an interesting idea, but unless someone big picks it up, like Google, this isn't going anywhere. So it might be the future, but I doubt some new player is going to come in and take it to the point we are expecting it to be.
And this would be for geeks, right? People that actually know the difference between a GPU and CPU and the importance of RAM? Otherwise, I can see morons tacking on like 15 storage devices to bring their life stories around, or people simply buying it and not really upgrading the parts and still complaining about it.
And given the prices of phones today, no carrier is picking this up since it means no upgrades to more expensive phones, and so this thing is gonna be off-contract and probably upwards for a grand, or more.