Why do you think microsoft will have the most powerful console?
And in terms of online capabilities, SONY isn't very far behind imo and some would argue it's on-par at this stage.
And what makes you think SONY won't invest in another console? They need to make money, and if there's anything they should invest in, it's a home-console. PS3 is now making a lot of money for them.
What SONY could have next gen is being the only manufacturer really trying to capture the hardcore with the most powerful hardware and excellent exclusive software (like they have now). SONY is in a hell of a lot better position then microsoft when it comes to 1st party games. If Microsoft also go down this route then the'll be tough competition, and it'll be similar to this gen in many ways. If Microsoft go down a more casual route, SONY has won the hardcore audiences. All they need to do is give it an affordable price ($400 max), a stellar launch line-up (like the PSV) and market it well (The hardest thing for SONY to do). Does this mean it'll sell like the PS1/PS2? Probably not, but it'll have a market for itself, with little competition in winning hardcore gamers.