I would stick with the PS4 footprint, make it twice as tall, and use low rpm 80mm fans to cool the console. I would also install 1/2in risers underneath to keep it off of wood surfaces, which tend to bake most consoles. I would add in hardware based backwards compatibility and include robust DLNA support (including MKV and ISO playback). It would have GbE onboard and optional wireless external adapters so the wireless tech can keep up with the times. The wireless adapters would be reasonably priced. The controllers would have user replaceable batteries.
All games would have physical media + CD-Key DRM or optional online authentication DRM with a 1 week offline mode. The console would ask every month for the original game disc to be inserted or the user could agree to online authentication DRM with the ability to revoke the license for resale purposes. Gamesaves and games could be downloaded from your home console via P2P protocol when you sign in on another console with your account. Multiple games could be played on multiple consoles under one account provided you insert the original physical media. If only one game is being played on one account, then normal DRM policy applies. Digital downloads could be resold within the walled garden of the console's marketplace to people on your friends list, and those funds could be used to purchase new games. Also, I would offer a mailed physical backup for the cost of manufacturing + S&H as an option for any fully Online digital purchases. I would include automatic game updating and scheduled gamesave backups to local media as options in the software of the console. Finally, games would be playable on a remote screen that simply streams the video output to the screen via wireless or wired connection, and the games are played normally with the console's controllers; this is an optional accessory.