Konami already makes money in this field. Honestly though, I think Nintendo's approach will be panels that you can put around the room. This will be aimed more at Japanese style apartments and smaller rooms/houses.
Here's the pitch for this tech. There will be a central hub/dome that communicates with the panels. Each of the panels is essentially a big, touch sensitive button with a small array of lights, a camera, and sensors in it. The central hub would be an upgradeable cube with the ability to talk to Nintendo panel capable devices.
Here is how the user experience would work for a normal Japanese home life.
You come home from work and take your shoes off at the door. Before you step into the main part of the house the panel detects your motion and lights up RED. Touch the panel with your palm and say "Hello." The panel records the immediate state of your hand, the rapidity of your voice, and responds with a response matching your heart rate, facial recognition. "Welcome home. The time is 1700. You seem stressed. Would you like to relax?" or "Welcome home. I trust your day was good?" or "Welcome home. Are you okay? Should I contact someone?" You respond with simple commands like Yes or No. Nothing particularly complex. The panel sends the information to your hub which sends out information to smart phones, PC apps, your Nintendo video game system, and other items. The information recorded is stored to keep track of your health or the health of other people. The hub would then make suggestions on your devices as to diet, exercise regime, sleep schedules, and so forth. It sounds complex but it's simple in nature. You just touch the panel.
You have a family. Your significant other and two kids. One of your kids comes home, touches the panel, and that information is sent to your smart phone and PC at work. So, you know they made it home from school, they seem okay, and the panel camera snapped a picture of them when they came home that you can now view. The panel detected that their temperature is slightly below normal. This means they are probably hungry. There's some food in the fridge. Send them a message to eat. The hub would then sound off: "There are snacks in the fridge, -insert child's name-. The estimated arrival home time for -insert your name- is 1930." The hub would also keep track of activity in your DVR or other devices. The hub would allow you to remotely set your DVR or settings for other items as well as make recommendations for food to order or purchase.
One item that would be excellent for Japanese apartments or individual rooms would be light wall projectors. These are wall mountable light/camera arrays that allow surface manipulation. Several E3's back, Nintendo had interactive Koi ponds in a section of their booth. When you stepped on the floor in this pond, it caused ripples and waves. You could sink stones in it or interact with the fish in the pond. An item like this projected onto an empty wall or other surface is one item you could activate. Example: You come home, touch the panel, and it notices that you are stressed. "Would you like to relax?" If you answer "Yes." The hub asks if you would like to use the wall. You could say yes and it would use the light projection to add interactive imagery to your walls and surroundings to help facilitate a relaxing mood. It might raise your thermostat slightly or lower it slightly. The panels would be in each room. You could also set them so that stepping into a room and touching the panel would turn on the lights for you or turn them off when it detects that you left.
Okay. All of that sounds ridiculously invasive. But we live in a world where people publish damn near everything on Facebook or Twitter. Why not have the panel automatically update your Facebook status to tell people that you've arrived at home too? Your health is fine, you seem a little stressed, maybe the hub would suggest that you order out and then display a set of suggestions on one of your walls. Just move your hand over the selection displayed on your wall and confirm an order. Feel like Pizza tonight?
I dunno.. the panel and hubs seem like that is what we would get. Oh, the panels synch with other devices. Are you diabetic? When you go home, your glucose meter automatically syncs with the panel. It would compile the times that you checked your blood sugar levels. "Welcome home! Please be sure to check your meter at 1600." "Welcome home! Your last account showed low blood sugar. Please check your meter." it would also talk to other fit meter like devices. "Welcome home! You have not met your walking quota today. Are you tired? If you are not tired, I have sent a recommended. grocery list to your phone along with highlighted sales at Lawsons." You could also sync it to your bank and bills. "Welcome home! You seem stressed. There are three pending bills due in three days. Would you like me to handle those? (Administer one time auto-pay)"
A lot of those features would be automatic and it wouldn't explicitly tell you what it was doing. You come in, the panel glows red until you touch it. When you touch the panel, it turns green or blue. For people who are color blind, you could set it to pulse rapidly when you come in and then stop glowing after you touch it. If you have vision problems, you could set it to make a small beeping noise until you touch it.
Please touch the panel. Just musing a bit.