Pardon me necromancing a thread...
I remember a William Gibson novel, where one of the characters had a computer called a "Sandbender". The concept was that the case, keyboard, etc was the big investment (including semi-precious stone keys), and all the guts were made to be universal. Kinda looking at the same concept here, methinks: several case manufacturers would make cases to fit the different sizes of "Blokphone", with component manufacturers standardizing the pins and such (similar to how we've standardized the charger plug on micro USB). Initial investment would be higher than a typical "flagship phone", but would work out cheaper in the long run... assuming the component price was somehow kept reasonable. Think about it: spend $500 on a phone that only needs $150 in upgrades over 10 years, or spend $150 every 2 years for the new phone?
The only real hurdle I see to dev is the big companies (Samsung, Apple) fighting it. And I don't ever see it catching on mainstream, but rather a niche market
Personally, I would LOVE it