The 10 year plan doesn't mean anything except that Sony will still be selling meager amounts of its systems after years six and seven while other consoles may fall by then. Look at PSP - the system is getting replaced in 2011 by all accounts, and PSP is already pretty dead and its only seven in the West. The hardware companies tend to release new systems when software revenue for their system dries up. Past a certain point it doesnt matter how big your base is, since it isn't buying games anymore. PS2 has the biggest hardware base of all time, and its completely irrelevant as a market to most publishers, except for Sony, Konami, Activision and EA which can still make a bit of cash on sports games and liscenced games. The irrelevance simply comes from the fact that most people moved on during 2005 to 2008, when the "current systems" went from a base of 0m to 100m units or whatever.
Its not like other companies didn't accomplish that - NES still had games chart in Japan semi-regularly as late as 1991, in its 9th year. NES was still selling in the west in 1993 and 1994 at somewhat respectable numbers.
I also don't think people really reach a limit. Some genres are exceptionally resilient on a given platform because thats where fans concentrate. Its going to be years before something replaces Wii as a powerhouse for platformers, X360/PS3 as a powerhouse for shooters, etc, etc.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu
