NEM's main chain is fully decentralized and uses the same APIs as Mijin.  Mijin is a private fork of NEM that has been optimized for speed and security.  It is a way for banks and/or other large businesses to figuratively speaking "dip their toes into water" of blockchains.  They get full control of their chain, get to build assets and trade with partners they trust.  

Later on if they want to start to trade on a public and open chain with anybody and everybody, in just a few minutes they can have their software ready to work on the NEM main chain.  

With one major banking testing this, and 5000 Japanese companies becoming connected to NEM via Infoteria adapting Mijin, it is reasonable to assume that some will also move off of Mijin and additionally run services on the NEM main chain.

And of course, we hope to sign more contracts and gain more partners too.  If/when those are signed and press releases are issued, then I will update here about that too.