Honestly I don't see Nintendo loosing their handheld market in 10 years. Nintendo is a company that adapts and innovates to continue market dominance. Now will Nintendo be selling a stand alone gaming handheld in 10 years? Maybe not, however I have no doubt they will have a handheld device on the market.
Your seeing with Sony already the idea of creating a handheld game console phone. I could see Nintendo creating a phone like device in 10 years. A device with phone capabilities not a phone with gaming capabilities. Unlike the I-Phone or Sony's new phone Nintendo will probubly not release a stand alone phone.
My best vision for 10 years from now is a Nintendo multimedia handheld. A handheld that will have apps (Like DSiWare and WiiWare or Appstore apps like on I-Phone) it will also have phone capabilities so that is someone wants to use it as a phone they could go get a plan and Woolah. I also see it using video chat like Kinect and a free phone like service much like Skype. The device will still have games at its core with software being slightly cheaper (9.99$-39.99$).
In the end I think Nintendo will adapt to the market. Sure consumers like to purchase their 99cent-5.99$ games on their I-Phones and such but their will still be people willing to shell out 29.99$ for a good game.
Now Microsoft and Sony are in similiar boats. In ten years will their be a new X-Box or PlayStation? With cheaper games coming out for pick up and play and higher profitability of FaceBook or Apple games is it feasable to continue having a high end gaming platform?
I think Nintendo will remain in the handheld space probubly another 20-30 years in some way shape or form. Sure they will evolve to compete with multimedia handheld devices but I doubt they will dissapear altogether. Also considering handhelds have always been Nintendo's strong point I don't see that changing drastically even Apple can't kill Nintendo's handheld devices.
Now will their be a PSP3 in ten years? Maybe not but Nintendo is here to stay!
-JC7
"In God We Trust - In Games We Play " - Joel Reimer







