Modi should make a deal now for the Su 57. This is the right time. The Russians are very willing. Talking abt tech transder of even the S 500. We should start manufacruring in HAL's Nashik facility immediately. Target abt 400 Su 57 in the next 9 years until AMCA production begins.
My reasoning for buying Su-57 is, preset IAF future plans like below
1. Tejas Mk1 will fill in the place of retired Migs (12 sq) timeline 2027-35
2. Rafale will take-up the rolls & place of Mig-29s & Mirage (8 sq) timeline 2028-40
3. Tejas Mk2 and later will replace Jaguar and will be backbone of IAF (20+ sq) timeline 2029-45
4. AMCA will be in small quantity and replace Tejas-Mk1 & Su-30s (12 sq) timeline 2040-50
above will make upto 38-40 sq but minimal requirement is 42 squadrons
though on paper it looks like IAF will have 40 sq by 2040 but AMCA is just on drawing board and not reality, Tejas Mk2 yet to fly and if everything goes as planned its delivery schedule might starts by 2030-35.
by 2035-40 initially inducted Su-30s will be at the end of its life (i.e., 30+ years of induction) and this leaves out need of 8-10 sq of Fighter Jets. options available Infront of IAF are either buy Su-57s (available) or F-35 (buying will be irresponsible) or order more Rafale but issue is delivery of present order will start only by 2028-30 and scheduled upto 2040-45.
But your reasoning on anything in regard to the IAF's future acquisition is irrelevant, these are at best wet-dreams!
1. Tejas Mk.1/1a will surely come but it is now too late, it is simply not capable enough, as the IAF no longer needs a MiG-21 successor.
2. & 3. yes, sounds great, but the Rafale until 2040s! Come on ... yes, capable as it is but for the 2030s-2040 against a true adversary it's too late. And the same with the Tejas Mk.2
4. IF, IF, and this "IF" grows with each repetition. The point is, if India doesn't finally start truly investing, working, and changing its structures (like we in Germany should do), nothing will change, it will fizzle out, and even in 2049 fanboys will still be promising that AMCA "will be whatever, but surely the best 5th generation type ever!"
As such, on paper it is a nightmare against any Indian aspirations and even more so compared to the Indian self-image! Wake up already, otherwise nothing will change, except that India will continue to be taken lightly and financially exploited.
And as for Russia, that old man can barely manage his own unsteady gait. Do you really believe—especially since the IAF has rejected the Su-57 again—that you can achieve a) licensed production, b) technology transfer, and c) sufficient production numbers in a timely manner? NEVER!