If 1 XEM = 1 USD, then NEM network would be worth 9 billion USD - it's more than BTC today. Everything is possible, but I have impression that unfortunately NEM is being undervalued by crypto community. Its closed source, and not easy to use for average Joe. Obviously I wish it was 1 USD cos I hold small stake just in case :-)
If 5-10 years down the line the crypto space isn't considerably huger than it is now then something went seriously wrong. I imagine there might be a few systems around that value level by then. I think B2B will be where it's at. Average Joe still won't have a clue about any of it.