There are a few issues, all very important that Apple has to address if it wants to release a bigger screen iPad.
- Right the right size screen - it's not so simple. Apple designers have to find one that balances the needs of the users, the UI and gesture experiences, and the technical feasibility.
- Bigger screen would also mean a CPU with the right graphics processing power to potentially drive more pixels. This new chipset would have to be able to do that without drawing too much power.
- A newer battery design and packaging to allow for a bigger battery to drive the screen and new internal components.
The screen size might be perfect from a UI standpoint but only if the mobile chipset can provide the adequate amount of processing power new features and graphics muscle to drive it all without compromising the battery life. Then Apple has to make sure battery design has progressed to the point where it can provide enough power for screen and the electronics.
All that will then have to fit within the new thinner design that Sir Jony Ives has come up with.