PS3 and 360 are already set top box devices. Slap a decent browser in the PS3 and you've got all the entertainment device you really need. I do think Sony should put an Android OS inside PS4. Android being open source, Sony boffins can take ICS (or the next one) and customise (and secure) it for the PS4. That way you can then have Android tablet and PS4 interactivity. MS is doing it with Windows devices and XBL. Apple has all its HW integrated. As long as Sony doesn't limit tablet integration to Sony tablets then Android device integration will be a great selling point.
Google and Sony really should be tech buddies because they have a lot of common enemies, and really nothing in the way of direct comptetiton between them. Except now that Google owns Motorola Mobility (or soon) they will be directly competing in smartphones, but there's plenty of room in that market for them not to step on each other's toes.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
