The big issues: View
Let's think beyond the scope of one monitor/tv and space. A gaming household would be interested in an entire room. Handheld screens are also the path to take. However, in gaming terms, adding another tv requires extra power from the computer/console. This could be solved by making the client into a server and have an extra computer linked... If not more. This is happening in terms of super powerful computers, but the bottleneck becomes the game creation engine/technology. Making a multi-player server/client relationship, then adding a single player a.i. client over it is a good choice to take. An easy example to name for view is the First Person Game/Shooter.
The big issues: Control
Mice, keyboards, controllers, our body, handheld touch screens, you name it... It's pretty much accepted in human gameplay this generation. A problem exsists, however... It's seperated. Even our hotkeys are lost and not very easy to tinker with. Almost all keyboard users will claim WASD or ESDF movement, however, I've always been an ASDF movement player. A back, S forward, D move left, f move right. Take a controller player and they'll give you mixed feelings on where to put the control stick/d-pad. A horrible situation for a player would be where they want to swap the control sticks. This leads to very many problems.