Today's mobile devices are mostly dumb terminals for the cloud. It's a portable always on VT100 for the 21st century. Web sites and apps are like giant VT macros. All the interesting stuff is elsewhere.

As they get more powerful I could see apps doing more interesting things locally, but in doing this they will mostly be talking to distributed systems over a network. (E.g. peer to peer net in apps.)

The last bastion of the box is PC, but that is also a mature and stagnant platform whose use cases are mostly served by what is already there.