When EU was running great, Turk was sidelined.
Turkey still gets billions of euros in "pre-accession funding" and most foreign investors in Turkey are from Europe and a 50% of its trade is with the EU. So Turkey still needs Europe and Turkey is a good place to invest in. Whatever criticisms I have of Erdogan, it must be said that he has been good for business.
My own view is that it doesn't really make sense for Europe to pursue seperate fighter jet programs. Ideally, every European country, including those outside the EU like the UK and Turkey, should have a single joint program. If that had happened, Europe would have its own 5th gen fighter jet and its own fifth gen engine. But there is too much nationalism in Europe. Look at the French cutting off from the Germans during their joint jet project.
This problem of fragmentation is at the root of many of Europe's problems. When people ask "where is the European Google?" it's the same story. Because there isn't a unified federal state. If there had been, there would have been one. That's one big advantage China and the US have over Europe. I guess having a single language helps a lot in this.
So as long as this remains the case, various European countries will have to self-fund their national efforts even if it is clearly subpar compared to what could be achieved if everyone joined hands. But this is easier said than done. If you look at KAAN, you could say it represents a national success for Turkey. And it is. But it also represents a failure for Europe, because in a better world all countries in Europe would work together instead of going their own way or split up into tiny groups. Fragmentation is the number one problem.