SU-30's can replace F-14, F-5 and F-4. The F-5 was not a very good plane to begin with, if one looks at the Iran-Iraq war, that becomes apparent. Jf-17 is a simple waste of cash bro. Why spend money on that when that money can go elsewhere? Remember bro, Iran even rejected the J-10, nevermind the Jf-17.
The problem is, even if we received the SU-30's tomorrow, their usefulness would not last for more than a decade. They will provide only a very temporary solution. Iran needs to :
1)Think about purchasing the PAK-FA and see if Russians will allow any level of tech transfer.
2) Start own Co-development of a 5th gen plane with foreign aid, preferably the Russians.
What happens beyond 5th gen remains to be seen, perhaps 6th gen will mostly be unmanned. Iran is already in a very good position for unmanned system, we must not lose our momentum in this sector.