Listen, PS4 is going to require you to pay to play online. Not for netflix or other cool features, but for multiplayer. It'll be cheaper than XBL but it's still not worth it.
The PS4 will not be backwards compatable with PS3 and PS2 games, the PS3 can be modified to be backwards compatible.
Currently I have a PS3, Xbox 360(Not Jtag, plus it's one without the removable HDs.) and around 7 medium quality PCs.
PS3 wins as far as consoles go, but if you're going to dump the money into something NEW, buy a PC and get a warranty on it. Might cost you $200 more to get a decent build, but you'll be able to do 6x the amount of gaming, and honestly won't need to upgrade for a couple years.