Phones are effectively PC's, and will more and more take over their role. Anyhow, there's a big fat 'I told you so' to whoever I was arguing with on here when I predicted this day would come many years ago :)
POS systems (as you know them) won't even exist in the future! Think forward. Sorry, but Microsoft is dead. They have zero vision, because of this, they will play no significant part in the future of computing.
That's a fair guesstimate, but I will raise it to $3521.13 by then they will be selling robots, an assortment of wearable devices, digital wallets will have surpassed cash and credit cards, fabrication machines maybe, hell, perhaps even an Apple TV!
Android will suffer the same fate as MS. It's hard coded into the business model. Watch as it fractures, gets more riddled with bugs, security issues etc as they all fight for control. It's just new, they had a chance to start afresh, that's all.