sony has strong legs due to continued ps2 and psp sells. Also, each ps3 earns them both a gamer and blu ray user.
Nintendo has 0 competition in both home and handheld consoles when it comes to casual/non gamers so they got some legs too.
MS gave up on the origanal XB very quickly (only 4 years) and they weren't able to get many HD attachments into the hands of consumers. I don't know how soon it will be, but I feel if a company will go, it will be them.
And yeah, Apple with make a console and/or mac game push sometime over the next 5-10 years.