EU has no actual bite without US support. Even if Iran tests one of its SLVs with a RV as an ICBM (Qassed for example) or launches Sejjil-II at its full apogee (may cross 3500 KM) EU will not launch a war on Iran, sanctions may come but after a nod from US. Almost all governments are Jew Debt playgrounds except few. If US does not involve itself then EU won't.
This time, US demand is more crippling because there is just no way Iran can disguise an IRBM or even a hypersonic MRBM like Fattah or KS as "500 KM". They will literally have to claim 3 Tonnes of warhead for these missiles to justify their existence under whatever lame ass deal Araghchi cuts with Khamenei's backing.
See 2000 KM was JCPOA outcome and was quite workable for IRGC. They had to give hilarious explanations for Sejjil-II, K-4 borderline IRBMs which they labeled as "1800 Kg warhead" for 2000 KM range. IISS themselves estimated them to be capable or reaching ~3500 KM with regular 650 KG warhead. So it was workable. 500 KM means Iranian strike arms will be gone forever and be reduced to Turkey, Egypt, KSA levels.
By no means a MIG-29/35 airframe can provide strike capability to Iran as a substitute to IRGCAF's devastating missile strikes. Its just an old interceptor whose only utility in a modern combat is in form of a point defender with R-77AE+R-73M package. It cant carry long ranged BVR, does not have a modern AESA radar, does not have range or avionics to support itself venturing out of Iranian airspace over Iraq to resist IAF launching ALBMs. IRIAF can secure Persian Gulf against PGCC or Turkey-Azerbaijan theatre with them but IRGCAF's reciporcating strikes are far more heavier deterent than flying these interceptors on borders.
Saying that, I have always been highly in favor of IRIAF rebuilding itself around MIG-29 because it will not require any training, infrastructure establishment etc. Iran asked for 72 of these in 1991 with plan for 148 of them along with MIG-31. So if they come, they are OK but not at the cost of IRGCAF's missile capabilities.
Khamenei has killed the SU-35S deal if BT written article is to be believed (posted few pages back). I am assuming IRI used SU-35S deal as a bargaining chip against some demand by US+Israel. May be US+Israel asked for complete bundling up of Missile Program but with a large fleet of SU-35S and with experience of firing hundreds of solids fueled sleek MRBMs for years now, Israel got afraid that with such a large strike aircraft, Iran may switch to its own scary arsenal of MaRVed-ALBMs. SU-35S carrying ALBMs means Iran firing ALBMs from over iraq or even from within Iranian territory at Israel (no boost required). This is why A large fleet of SU-35S/SU-30SM in Iranian hands is a big no no for Israel. They will be fully happy with large number of MIG-29/35 in IRIAF colors in exchange for missile ranges curbing + gaurantees of no SU-35S in Iranian hands.