Jigs, I don't mean to step on your toes brother but that whole "Russian equipment cannot be compatible with NATO systems" cliche is usually just blown out of proportion and has its roots in some very old mass misinformation dating back to the Cold War era.
The problem is almost always SOFTWARE, rather than hardware. Both Western and Eastern aircraft use the same electronic subcomponents, same chips made in Taiwan, etc.
Sure, the West might have switched to MFDs and glass cockpits a few years earlier, but we should call that what it is; having technologic edge, and not "incompatibility".
Greece has been quite successful in integrating their Russian-made S-300s in NATO theater defence over Greece, and a significant number of old Wasraw Pact and even ex-Soviet Union countries are now NATO members while still using predominantly Russian aircraft.
Romania, Bulgaria, Latvia, Lithuania, Croatia, Czech Republic, Slovakia, Slovenia... are all NATO members with extensive use of Russian aircraft and other Russian or ex-Soviet military platforms.
PAK-FA is a new generation aircraft with cutting-edge electronics; claimed to be on par with the F-22. I really don't see why Turkey shouldn't be able to implement it in our national defence doctrine and use with the existing F-16s given full TOT from Russia, natinalization (source codes, subcomponents, etc) and local production.
By the way, I think it'd be wise to point out that most of our F-16s are and the upcoming F-35s will be completely "incompatible" with our indigenously designed and produced missiles and munitions... Food for thought.