The market for low end voice/text-only cell phones will get taken over by low end smart phones[..]
I wouldn't be so sure. It depends a lot on what people want. And so far only about a fifth of mobile phone owners want a smartphone.
Are you so sure that the smartphone form factor is such a universally desired one? Not everybody wants the "Jack of all trades, master of none" that is the smartphone. I for one see perfectly good cases to be made for combination of a dumb but reliable phone (you know, that makes and recieves calls and does it well) with other devices: MP3 or video players, tablets, netbooks, laptops, PC, gaming consoles, portable gaming devices etc.
And let's not forget that the so call "dumbphones" are not exactly dumb, they're really "feature phones". They have added functionality that serves their owners perfectly well. Actually, what these people are holding back from is not the whole smartphone experience, it's certain things they see as drawbacks: all-touch interface, big [fragile!] screen, low battery life, permanent connectivity, big price tag. Are these going to change? Some will, some won't.