My CPU is getting up there in years and my PC is an OEM build, so no overclock here. I've seen where Watch Dogs has massive CPU requirements and noticed that Crysis 3 is nearly maxing out my CPU. I read where the latest Nvidia drivers are supposed to reduce CPU bottlenecks and the next-gen GTX 800 series video cards will have integrated Tegra CPUs. I'm a bit concerned about my CPU possibly bottlenecking a GTX 870 when that comes out, but I learned that Project Denver should reduce CPU bottlenecking. I'm using the stock CPU heatsink and the CPU will average about 78°C when running AAA games. Is it safe to say that it's worth upgrading to a 4770k and z87 motherboard, wait for 5th gen Core i7 and compatible motherboard, or keep what I have? I don't want to spend about $700 for a CPU / MB / Windows upgrade unless I have to and I know that X58 motherboards are hard to come by these days.
It's still a good processor but you would benefit greatly by upgrading on either side Intel or AMD. Watch Dogs looks to be a very multithreaded game judging by the required CPU's. I think the requirements for the game are a bit over exaggerated though but they stress the fact that they want you to have as many cores as possible. What surprised me at first was that the CPU in the recommended requirements section was the i7 3770K and not a core i5. But I think why they put the i7 there is for its hyper threading. So since your CPU has hyperthreading it might be able to play the game pretty decently but there's no way we can find that out until it releases. I can tell you that the Core i7 950 is miles ahead of the Core 2 quad Q6600 that is in the minimum requirements.
Your processor is still very powerful and you should not need the upgrade. It really depends what gpu you plan on pair it with. I would say anything as good better than r9 290/780 will require an upgrade. Upgrading to i7 4770k is a massive one but would require an new motherboard and the hyperthreading won't help in 90 percent of games and i5 4670k perform just as good unless you plan on spending more than 1000 dollars on gpus. Your processor can run watch dogs with no problem as long as the rest of your parts are up to pair.