Personally, I think everyone has learned from Sony's mistake. Every console manufacturer will likely stick to similar architectures.  Although Microsoft will have the most powerful console, it won't be by much. It will simply be for bragging rights.

Microsoft: Personally, I can see Microsoft sticking with IBM + ATI for simplicity and backwards compatability. I don't know why but I think that although Nintendo proved that raw power isn't needed, Microsoft will simply not let Sony have the performance crown. They will probably capitalize on the fact that Sony can't spend too much money developing another powerhouse and will bring out their own. The Power 7 CPU will be available next year and may be viable for their next console. The power 7 will give them 100% backwards compatability with the Xbox 360. Another ATI GPU seems logical. The highest current generation R700 GPUs already break 2,000 Gigaflops, by the time the Xbox 720 comes out, 2Teraflops should be affordable for Microsoft. Microsoft will cave in and use Blu-ray.

Sony: For better or for worse, Sony is stuck with the Cell architecture. Any attempt to switch architectures would essentially make backwards compatability with the PS3 impossible and waste millions spent in research. Luckily, by the PS4's launch developers will already be familiar with the Cell architecture and should be able to exploit its raw power without too much trouble. The Cell2 CPU is suppose to come out in 2010, making it the logical choise. Unlike the Cell processor, it is not revolutionary, simple evolutionary. The PS4's CPU will definetely be more powerful than the Xbox 720's, however, it will most likely have a weaker GPU. The GPU will likely be an Nvidia GPU to maintain backwards compatability. Sony will stick with Blu-ray.

*Sony refuses to release the official specs of RSX. Although most insiders agree that it is 500Mhz, there are a few that say 550Mhz.

Nintendo: Nitendo is...Well... Nintendo... I'm not really interested in putting up specs for the Wii2. They will most likely be too similar to the Xbox 360.

And those are my predictions. I'm really interested to see what other people think will happen. Please try to consider the economy and each company's situation... Yes, it would be nice if Sony could once again release a revolutionary console, but they simply don't have the resources. Please don't post a Cell 2 CPU with 64 SPEs and dual G300... Same thing for MS fanboys, don't post crazy specs like a 16 core Power7 (I am well aware that they exist) or dual larrabees. 

"Nintendo: Nitendo is...Well... Nintendo... I'm not really interested in putting up specs for the Wii2. They will most likely be too similar to the Xbox 360."

Firstly I would like to say that unless Nintendo innovates again(which they probably won't at the level that the Wii/DS has) they will most likely make a console at least on par with that of the others Next Generation. The only generations where their console was noticabely weak were the 3rd(nes), and this one (Wii). Even if they do make a noticabely weak console, by then it will probably be much cheaper and easier to make a console more powerful than the Xbox 360/PS3 in the same sense that the Wii is more powerful than the Xbox/Gamecube. I just felt like I should express my opinion on this matter.

Although I agree with you that Nitendo may be forced to play the graphics game, any guesses as to their next console would be too random to even bother. Mmy specs are also guesses but most people expect similar specs out of those machines. I guess I could have created 2 different specs for Nintendo, 1 for the Wii2 and one for a more powerful Wii HD but I wasn't too motivated. I may update it later though.

by the time ps4 releases, sony will have money so they will make a very powerfull console once again.

You don't have to change your opinion because I disagree with you I just felt I should present what I think. Anyway what you said is pretty much the minimum I think Wii 2 would be seeing that Nintendo already stated the next console will be HD, and anything less than the 360 would not be really good for this(especially considering Nintendo likes games to run at the highest possible framerates). Next Generation though I don't think there will be a huge leap. This generation already feels smaller in leaping than last from 5th,and last generation feels like a smaller leap than 4th-5th.

Research and development for a console being released in 2011/2012/2013 would already be pretty far along. It doesn't matter how much money Sony will have then, they are working with the resources they have now. Also, what if they sink more money in the Playstation and the PS4 flops and sinks the entire devision/company? Even if the PS3 will end up being on the market for much longer, if Microsoft and Nintendo release their consoles, Sony will be forced to release the PS4 at the same time. Launching a console in the middle of a generation is extremely dangerous. I don't think Sony can afford to take too many risks.

The reason it feels smaller is because after a certain point, it takes more power for smaller graphical improvements. The PS2 to PS3 jump was actually a lot bigger than PS1 to PS3. 

XBox370: same, smaller package, and with a new controller. Maybe a faster Xenos GPU, and maybe 768MB unified memory. 320GB HDD.

PS4: Same CPU, but with all 8 SPUs unlocked, instead of just 7. Hella faster "RSX 2" GPU, and 1GB memory (512/512). 320GB HDD.

Wii HD: 1.5 GHz "Super Broadway", 2x 350 MHz "Super Flipper Bros". Has HDMI, has DVD playback. 80GB SSD add-on. Okay, yes, I'm making a joke with the GPU.  Maybe a 500MHz Flipper 2 with shaders.

Yep. I'm predicting the next gen will merely solidify its ability to play HD games, and not jump the gun with crazy new tech and costs, for both the console manufacturer and developers. 1080p at 60Hz is all that's needed, and I think the console makers will do only what's necessary to hit that bar. Nintendo won't, because I don't think they care.

 microsoft is going to keep the 360 out for as long as ps3 is out. they have already said that.

Hmmm, with those specs you threw those consoles won't have a friendly price at launch. And that isn't good.