I've been a designer and I can't see a reason why it is not possible to make such a passenger aircraft in 6-7 years eswpecially when:
1. You're not going to make the engine.
2. You already have experience in making cutting edge fighter jets.
3. You don't have to reinvent the wheel.
I can't see how difficult designing such an aircraft could possibly be. The only problem could come while looking for vendors for manufacturing the aircraft but even then I feel that if you have the market, the vendors will come up on their own.
its more complicated than that u listed``first of all, a passanger plane consists of literally 'millions' of parts and components`and even india is be able to build fighter jets, however there are different concepts and attribute priorities sharing between civilian ones and those military ones```the formar one focusing more on duability, reliability and costs, so that involves different lines of matierial sciences and designing concept from the military craft, like the wing nd fuselage ratio, shape and thinkness etc```
you need thousands of hours of simulation and ground tests to testify any possible layouts and designs, in order to check any aerodynamic errors or gliches before to build a prototype, which will carry out real flight tests.
if that as easy as you claimed then why at the moment only U.S and european unions are the only two can build big comercial civilian planes, even russia can not claim that positon as their civilian planes have seriouse safety and reliability issues but they do hv good fighter jets``so that demonstrates the fact that technologies involve with civilian plan are quit different from military ones``
yes, in some case vendors will comp up with something to fill the market needs, but again in aero industry you are talking about high tech and investment and technology intentive vendors, at the moment we only see these kind of vandors from IT sectors in India but hardly from other sectors``
Do you know china successfully tested 70-90 seats RTA in 80s (called Y-10, u can look up) but that project was cancelled because of the reason you just listed--vendor factor