If a phone manufacturer used their noggin and created a decent handset (swapable battery, microsd, current mid-range specs) with long term support and a yearly cost of say £20 they would take the market.
Yeah, and if they throw in a pony they could corner the market of girls aged 4-14.
But before a commercial company is going to do something, there needs to be a way they (think they) can actually make money doing it. Just "taking the market" isn't much of a benefit, if you're losing money on every sale.
Long term support of phones is difficult. Difficult means expensive. "£20 per year" wouldn't begin to cover it; and who would be willing to pay £200, which is probably closer to the real cost?