What you're essentially saying is, how do we know people want "Next Gen" consoles?
Demand for home consoles and dedicated portable gaming devices are completely different. The core of the games industry lies in the home console market and the future of the games industry lies on the ps4/720, who will undoubtably share most AAA titles (Unlike 3DS/Vita). In the immediate future we will just see cross gen games will superior ps4/720/PC versions, but going into 2015 it will likely be a case of; you want to play the next big thing in gaming? Well you're going to have to buy a new machine to do so.







