You will still be able to play your Xbox 360 for a few more years. Thing is, you won't get the better more awesome games on it because it can't run them. There isn't more that can be done with current Technology. There is a new console generation needed - even if you don't want to use it.
Consoles have been holding back gaming for a while, and I'm not just talking PCs. The longer we stay in this generation, the less new stuff we will get. Hell, some devs like Crytek may even become PC exclusive as they become sick of trying to make their games work on consoles.
With new hardware we get the possibility of better AI, better Graphics, larger levels, more possible interactions within those levels, widened FoV, you may get splitscreen with high detail again, more things on screen at once, higher framerates, dependent on whether bandwidth limits are raised too larger online matches - everything will improve. Hell, the market when a new console comes out is high-risk, which will allow devs to make more games that aren't simply clones of others.
If you don't want anything to improve, don't buy the new console. Stay playing these same old games on your Xbox 360, and let us play the new stuff.
Hell, if you're worried about how expensive it will be - get a PC. I can guarantee you a lot of people with PCs from 6 years ago won't have to upgrade when this console cycle ends. They may choose to by choice, but their PC will last through the next gen of consoles too, maybe with a $100 graphics card upgrade midway through.
That said, it will come down to the specs. If they have 1Gb RAM, a single core processor a little faster than the previous, a 320Gb Drive and the effect of a 9800GTX, not worth it (The 9800 was a legendary card, yes, but it does not support modern gaming features, and is not properly equipped to live in this day and age).
What I expect from them to be worth a purchase would be 6Gb RAM, Quad Core processor, 1Tb Drive and the effect of a 560Ti. That will bring them on par with mid range gaming computers. They'll still be outdated by hardware standards, but not by a ton, and especially not when compared to the low end gaming computers.
What I find amusing is that everyone supports the Wii upgrading, 'because it needs it', whilst the Xbox and PS apparently don't. IMO, its the other way round. The Wii is fine for what it tries to accomplish: Casual gaming experiences with low end graphics, made to be that entertaining thing that you sit down and pay for a laugh.
The Xbox and PS are now failing at their goal - to provide a cross between hardcore and casual gaming, where you can play games not only that you just sit down and laugh whilst playing on a Sunday morning, but also where you can play the new and latest games in a competitive fashion.
They get 30FPS BF3, on the effect of low settings. That's not competitive. Games like Dark Souls lag at times, and they'd hardly be taxing games on even semi-reasonable hardware. The PS3 is having bad lag problems with Skyrim. The PC version, according to some modders who edit the engine, is not at all optimised for the PC, yet a mid range PC will play it without problems.
There is no reason not to make a new generation of consoles, and there is no reason not to make them well. These consoles were fine for six years ago, and have now outlived their usefulness. Devs have to spend money finding ways to make consoles run games, as opposed to just making them and knowing the hardware will handle it. Things need to change. You want your old games, play your current consoles and don't buy new ones. You want good new games, put the money into getting that new console, or get a PC. Don't expect your bad old hardware to be able to run the new stuff though, or get upset like that guy on Youtube who was pissed that the console version of BF3 was streamlined. Live with your choice, but let us have a choice.
