When reading articles about the F-35, you have to remember that the term "Fourth Generation" and "Fifth Generation" are terms that Lockheed Martin came up with to provide some marketing cachet for the F-22 and F-35.
There is no strong definition for the term and the best description that I seen is that "Fifth Generation" fighters employ stealth and undetectable communications. This definition is used with the F-35 to indicate that it will sneak up to enemy aircraft and launch missiles before the enemy aircraft know that it is there - the F-35 doesn't have the dog fighting capabilities of the F-22 or that of other fighters.
People seem to forget that the F-35's capabilities were first defined after the first Gulf War in which F-16s and other fighter-bombers could not detect Scud missile launchers or approach ones that were detected by other platforms before being detected and the launchers moved out of harm's way or camouflaged in such a way that they couldn't be detected. Then deciding that the basic platform could be extended to a SVTOL for the Marines and a carrier aircraft further doomed it's ability to maneuver effectively against other aircraft that were designed for air-air combat.
Unfortunately, the US(AF) has put all its eggs into the F-35 basket. I don't see there being a lot of opportunities to order more F-16s or F-15s (with the F-22 line shut down).
This means that in future conflicts, the US may lose the "air dominance" that has been used in war planning over the last fifty years.