No because the cheaper Su-57 for mass production would have the AESA radar and the improved engines. It would always be superior to the Su-35.
Because of mass production of it this would decrease parts costs for the stealth version of the Su-57 with RAM installed.
I know no other 5th gen currently has a twin seater but it must happen eventually. The HAL Sukhoi/HAL PGFA was supposed to be a twin seater.
Then port the AESA radar into a SU35 airframe.
RAM does matter only for X band radars, for longer wavelength it has minor effect .
And the attack radar on a fighter jet is almost always Xband. The Long wavelength radar may see a low observable but can’t be fitted to a fighter. It’s only good for ground stations. As an early warning or large AWACS. Even then it can’t get the quality of return needed for a kill so an Attack Radar has to be used.
What you want to mean by "fitth percent " ?
To reduce the detection range by half the RCS has to reduced by 94%.
I wasn’t giving exact figures but that’s my point to get a substantial Reduction in range of detection you need a huge amount of investment in Stealth of the aircraft. Skimping on the RCS doesn’t help you it hurts you. If you skip a feature of stealth you might as well kill the program and port its avionics to a 4.5 gen.
Quite easy, if the RCS is one meter sphere can be detected from 100 km, a 25cm sphere can be detected from 50 km, 6.25 cm from 25 km and so on.
The above calculation true only if the wavelength is way smaller (magnitudes ) than the object.
And getting those require Shaping, materials, Coatings, internal weapons carry, serpentine inlets and more skipping parts of that increases the RCS back up substantially. And so the range of detection goes up substantially. SU57 is meant to close in and attack. But if the range of detection is 100km then any other fifth gen it might meet will see it first and kill it first.
Since the Attack Radar is an X band that RAM is critical. The long band issue you keep harping on is for thin ram around features like vertical stabs.
In Serbia the Serbs had a good intelligence network who learned the routes of travel for F117 and told them that The SEAD birds that were hunting SAM sites were grounded as their base was rained in. F117 lacked any organic countermeasures or ability to detect radar and missile threats. Modern Fifth generation fighters are loaded with countermeasures and electronic warfare systems as standard.