Thank you all for the answers. These are your answers:
1) Kaan will replace F16s. Eurofighter will replace F4s.
2) what is the earliest KAAN could reach FOC with the Turkish air force?
3) Because we need the fighter jets today and not tomorrow.
4) Its also called not putting all your eggs in one basket.
5) The Turkish air force is currently alarming. While there used to be 200+ F4 phantoms and 200+ F-16s, now this number is: 235 F-16s, 30+ became F-4
5 different opinions and I can add also my own opinion: The Eurofighter purchase is not definitive yet, nothing signed yet. So if I try to make sense out of it (my own opinion) Turkiye is probably trying to get a deal / license to build F110 engines. If the US does not guarantee the sale of F110 than the spare option is to buy Eurofighter and deliveries of Kaan with indigenous engine will become beyond 2030. This is how I read the situation.
As we can see, none of us know the real situation why we need the Eurofighter, everyone is trying to formulate a logical sense out of it. All viable reasonings, yet again all of them our own interpretations.
I wished SSB and our air force provided their reason. It is so flimsy when they say we need them without reasoning why, while we work hard on our own 5th generation fighter jet. I see this as sabotaging our own program .
I use the hard verdict of sabotage, cos this is the reality for or situation. We already buy 40 new F16's, add also 40 Eurofighters it makes 80 foreign aircraft which means 80 Kaan fighters less.
We do not have unlimited petro dolars like S. Arabia, if we purchase foreign jets that will translate into sacrificing in the numbers of Kaan that we will purchase. There needs to be a damn good reason to explain why we go for foreign jets instead our own product.
I hope I did not bother you too much, my aim is to provoke a real deep thought on purchasing foreign jets and the consequences of it for our own fighter program