You will be waiting an awful long time for a new PS3 to drop to $100. Even with a price cut and/or a BF sale it will probably be 2015 before you can get a new one for $100
I don't know about this. I would think they would pop up on clearance and with promo deals while retailers try to clear their inventory. Along with Sony's penchant to re-release consoles.
I also think this is a great time to get in on a PS3 or 360. When a system nears the dawn of a new generation, it means the current get is getting it's best releases yet as the hardware is usually being pushed to it's limits and has it's best games at a great price, usually >$20. Meanwhile, it typically takes a year to start ramping up good games on a new console.
Bottom line, you can pick up 50+ AAA titles for >$20 now, or pick up the best launch and most anticipated titles that trickle out for $50-70 just to have the latest games, but I doubt they will actually compare to current AAA titles. We buy the console for the games after all, so I would stick with current gen until the next gen has actually proven to add something that actually earns your gametime.