For gaming, an i5 is all you'll need for quite some time... I run a Sandy Bridge i5 overclocked to 4.5 GHz with a 780 Classified GPU... zero bottleneck and I haven't met a game I don't have to VSync... Well, Crysis 3 gets ~50 FPS on ultra everything, but that's an exception to any list... if you're doing a LOT of video encoding, you could look into a FX 8320, Xeon E3, or i7... though the i5 will handle it fine... AMD is slower per core, and some games don't use multi-threading very well (such as Arma, DayZ)...
As far as the 8-core i7... it'll be VERY expensive and price/performance will be awful I'm sure... the thing you need to consider is that you're currently using an older model, low-end APU ATM so pretty much anything you buy would be a huge upgrade...
Another thing you need to consider is if you're mainly looking for something for gaming, very few games use 8 threads, and even less so utilize SMT (or hyper-threading). Though this may be trending upwards, even the ones that DO use it only give you an extra frame or two per second over an i5... basically, unless you're using the computer for home business productivity, it would be an awful investment to buy socket 2011, which would be an extra $300-800 over the 4670k (or 4690k Haswell refresh that is soon to be released)...
Bottom line... an i5-4670k won't bottleneck anything and will video process fairly quickly... a Xeon E3-1230 v3 is about $50 more and will handle video a good bit better but can't overclock... an i7-4770k is about $50 more than the Xeon and can be overclocked... Here's some pairs to consider just to give you an idea...
Socket 1150 4-core i5-4670k / ASRock Fatal1ty Z97 chipset
http://pcpartpicker.com/p/wDcgzy
Socket 1150 4-core (with SMT) Xeon E3 1240 v3 / ASRock Fatal1ty H97 chipset
http://pcpartpicker.com/p/8GhMTW
Socket 1150 4-core (with SMT) i7-4770k / MSI G45 Gaming Z97 chipset
http://pcpartpicker.com/p/hk6prH
Socket 2011 6-core (with SMT) i7-4930K / Asus Sabertooth X79 chipset
http://pcpartpicker.com/p/tjRL23
You'll notice how the price scales WAY UP on socket 2011... now imagine close to double that, and that's about what you're looking at for the 8-core CPU that still doesn't have a chipset released or release date... also of note... very rarely is your RAM going to bottleneck your PC, so I wouldn't put a huge stock in DDR4 revolutionizing the computing world or anything... best case, if you need more ram 3 years from now, it may be less expensive for DDR4... (though on the front end, since it will have JUST come out, you'll be paying for it)
IMHO I'd get the i5, or Xeon if I did a LOT of video editing...