Su-35 would be a nice addition to strike precisely bases and groups backed by Israel such as Komala/others if needed without entering neighbor airspace and saving missiles and achieving the best damage output against them without hurting civilians as the west PR always uses this against Iran, this Komala base and small terrorist groups and gangsters near the borders aren't suited to be struck by ballistic missiles that makes unecessary damage with their CEP, but precision bombs. And Su-35 has a big number of pylon to install Iranian/Russian/Chinese air to ground weapons and bombsThe era of sending manned aircrafts into SAM zones has long passed. Today, missiles and drones are the real Solutions. Besides the stealth unmanned interceptors are the future of air battles.
SU 35 is a good addition but just an addition nothing more. We won't be paralyzed without it. And our scientists are not sleeping, they are working hard to develop a trustworthy Turbo fan engine. Time consuming but sure to come.
SU 35 was in fact a fill the gap solution for the time being, when Iran finally develops own platform, you would see them behind IRIAF doors offering their retarded platforms.
It is not a matter of survival.
It would provide Iran a new platform to study instead of keeping the F-5 and also retiring the J-7N jets and the blind Mirage, and even Su-27 would be a good platform to study
Also to defend borders from small threats such as "malfunctioning Azerbaijan drones" that could enter Iran airspace