My friend wants a $700 gaming PC. He wants it so in so he can easily upgrade it for the next gen games. Thank you in advance!
Does he need any peripherals? An operating system? What resolution is his monitor? Are there any specific games he will be playing?
Including most of contents of this sticky would help a lot: https://teksyndicate.com/forum/build-pc/read-you-post-general-guidelines-build-pc/140909
just an OS and he has every else
I'd recommend something like this, even though its a little over budget.
http://pcpartpicker.com/p/NV6Rgs
As far as upgrades, the biggest thing he can do is replace the GPU or add a second one for Crossfire. He can also get an SSD and an aftermarket cooler for overclocking. Upgrading to an FX-8350 is another option but much less optimal.
http://pcpartpicker.com/p/sRJbCJ
Your other option is to go for an Intel system. I don't recommend it though. It might have a higher performance ceiling in terms of upgradability with the i7-4970k, but the i3 is kind of weak sauce it will need to be upgraded more than an FX-6350. Also, a 750 Ti can't be SLI'd with a second GPU, so replacing it is the only option to upgrade.
http://pcpartpicker.com/p/MCL2bv
A little over $700 with the OS.
I forgot to mention, the 750w PSU is for upgrading with SLI. It's a little overkill but it's also around the same price as the 600w atm.
I'm inclined to recommend this build so far. Although I'm personally not a huge fan of Powercooler graphics cards, it is by far the cheapst R9 270 is a great deal when it comes to price/performance.
Biostar and Jetway have some really cheap motherboards. I will never recommend either, even at 99% off. 
$720.87 (after rebate's offers)
http://pcpartpicker.com/p/NkK3mG
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($119.99 @ Newegg)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($29.98 @ OutletPC)
Motherboard: Gigabyte GA-970A-UD3P ATX AM3+ Motherboard ($77.98 @ Newegg)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($68.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($55.98 @ OutletPC)
Video Card: MSI Radeon R9 270 2GB TWIN FROZR Video Card ($179.99 @ SuperBiiz)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Newegg)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Operating System: Microsoft Windows 8 (OEM) (64-bit) ($97.98 @ OutletPC)
Total: $720.87
Price cut time.
http://pcpartpicker.com/p/jG4drH