I actually agree, and do believe that if US and NATO forces had to fight the Russians either in Ukraine or in the Baltic republics in the near future, they will get their asses handed to them in relatively short order. But this has nothing to do with technology comparisons. US and NATO forces are technological superior by a wide margin. It's their morale, training, and will to stand and fight, alongside US and NATO people's willingness to sacrifice and accept casualties that I seriously question and which will doom the West. I mean, if the Taliban can chase us out of Afghanistan and Iranian militias can chase us out of Iraq ....
Re. "Checkmate," the cost estimates are all well and good, but ultimately it comes down to performance. And I don't see much performance value in Russian 5th gen platforms at all. Take the MiG-35, built purely for export at a very low cost. Despite costing only a fraction of what Western 4.5 gen aircraft cost, nobody wants it. Yes countries want low cost, but not at the expense of quality/performance.
Also, talk of the F-35 being bad is just utter nonsense, being fed by ignorant idiot news media types. Every single country that has operated it has their pilots only raving about its performance. Yes, just like any other revolutionary platform, it is having some teething issues, issues that will be overcome in time. But it is very much a revolutionary platform for future air operations with incredible capability.