I do not belive, that there will be no more consoles. I have a gaming PC and consoles myself, so each got pro and cons.
A gaming PC ist outdated at least after 2 years. (Sure, there are lots of games that dont need that much hardware, like adventures and so on, but when it comes to High End Shooters like Battlefield or epic games like Skyrim it sucks with a 2 year old PC at release). A console usually has around 5 years, until a new version comes out. So the console is much cheaper from the begin and you always can rely on it, that games released for the console will be running on the console. If a game will be released in 2 years for X-Box i do not need to be afraid to need a new X-Box to play it. (Contra: When a console is released some years, the graphic difference between console and high end PC becomes bigger and bigger on new games.) So the console is cheaper.
A console is from my opinion safer for kids. When I allow kids to play with my WII, I rather do not need to care, what they are exactly doing in every minute. They cannot download illegal thousend of songs, they cannot touch by accidant some spam or virus mails, and while playing on WII noone ever asked me if i liked to see an asian mothter/daughter couple.... cooking. Also everything you buy on consoles, is bought with virtual money, where no debts are possible. Is there no more virtual money they need to ask their parents to give them virtual money again. They cannot make debts on real money and I dont neet to give them my credit cards data personally.
3) Even my mom can connect a console with her television, following the step-by-step guideline. I could tell stories what she did terrible things to my parents poor PC (who is maintained by my partner, me and their neighbors ^^)
Mobile phones, handhelds etc.: There have always been small games beside the big ones. From shareware games for PC, casual games like Sims, gameboy and so on. So for playing, when you´ve got only 10 minutes time or are waiting and dont know when to stop playing, they are ok. New casual gamers will also be more attracted by small games liky "Angry Birds" and so on, because of the easy game mechanic. But i think, there will always be a fraction of gamers who want "real games", which needs a console or PC.