In a fight with "real adversary" by your definition, F-35 is the single worst choice of all aircraft, barring downgrade to F-4 or similar, due to its extreme cost. Ignoring the MAD aspect of the issue, if you're facing a massed assault of decent air superiority aircraft in a shitty fighter that has barely any missiles and only frontal stealth, you're dead.
Current fleet at least has a chance because there's enough of air superiority aircraft that have decent to good performance.
And again, you appear to be ignoring the fact that F-35 is a terrible attack aircraft even if we pretend for a moment that Lockheed Martin isn't advertising it as a fighter. Attack aircraft's primary role requires it to have decent operational range and payload. F-35 has neither without external hard points.
And no offence, but in modern world, enemy will know you're coming. Political conflicts that result in massive conflagration between two major states are affairs that take months to appear. And once that happens, spy satellites AWACS aircraft and strategic search radars kick in. Stealth provides little protection from those, you will be spotted. It will only provide protection from fire control radars which cannot get a proper lock due to sensory deprivation, and considering the questionable stealth that F-35 has in the first place and the fact that Russians operate MiG-31s which will be locking on it from above rather than below, F-35 is still pretty much the worst choice.