The robots, which cost between $20,000 and $25,000 each, were reportedly rejected by Apple because they aren't precise enough. Apple requires components to be installed with a tolerance of 0.02mm, whereas the Foxbots are only capable of 0.05mm accuracy.
Foxconn is reportedly redesigning the robotic arms to achieve higher accuracy but this process could take several years. There's even talk of abandoning the traditional automotive robot frame and designing a more human arm with multiple fingers to achieve higher versatility, but this will take a lot of research and will end up costing significantly more than the current Foxbots.
Other OEMs might not have the same exacting standards as Apple, but I doubt the likes of Samsung or Motorola will be too keen on accepting manufacturing tech rejected by Apple. It’s possible smaller Chinese companies that specialize in low-cost unbranded devices and iPhone knockoffs might be interested, though.
Most phones and tablets are assembled mostly by humans simply because of the precision required. Most robots don’t have the manual dexterity required to drop tiny components into devices on an industrial scale. The technology required to make this work exists, but you’d have to design entirely new industrial robots to make it happen. That throws the economics off balance. It seems counterintuitive, but the phone in your pocket might be more expensive if it wasn’t handmade. Foxconn is looking to save money fast, so it used automotive robots as the basis of the Foxbot design.