Under the current circumstances I don't see the Iranian airforce even considering a 5th generation fighter for at least another 10 years at the minimum.
Iran should continue to focus on air defenses & its UAV industry. As we've seen in Ukraine, potent air defenses & UAVs, when deployed properly, can have a significant impact on the battlefield.
If any real R&D went into Qaher, then it should be turned into a maneuverable UAV platform. there are currently rumors floating around.
Iran really needs AWACS planes. The Iran-140 could be a feasible platform as a medium range AWACS plane. Also the plane could be used for military / civilian transport + regional civilian flights. However Iran needs to procure the original Russian Klimov variant of the engine, preferably built under license or technology transfers. The Ukrainian Motor-Sich variant, built under license was a complete & utter disaster. Recently Iran showed that it can build the airframe from scratch so it just makes sense.
Currently Turkey is working on a 5th generation fighter. It's pretty much an F-22 clone but it looks good. According to analysts, it will be another 5-10 years before it is mass produced. Its production will depend on whether or not Turkey can procure GE engines for the jet. The Turkish Altay tank was delayed for years because they could not procure German engines/transmission. Currently they're working on a domestic model, which of course takes time. Another option is to turn to the Russians or Chinese, although the Chinese domestic jet engines seem to have a mixed reputation.
The UAE was supposed to purchase the F-35, but there were several disagreements about the terms. The Americans wanted to give the UAE an inferior version compared to what they're giving Israel of course.
The Ukraine war has shown the importance of intelligence gathering platforms as well as air launched, stealth cruise missiles like the Shadow Storm missile the UK has given Ukraine as well as precision rockets like HIMARS. Although the Russians adapted and are said to be currently jamming HIMARS in an ongoing cat & mouse game.
Recently Ukraine began using the UK supplied Shadow Storm stealth, cruise missiles, hitting multiple targets in the city of Lugansk consecutively for the last 4 days. The biggest issue when it comes to the Storm Shadow missile for Ukraine is that it is air launched and Ukraine does not have very many jets left in its dwindling arsenal. Those it does have are often times shot down on a regular basis and in some cases they are destroyed while they're still on the ground. Considering what we've witnessed thus far though, I'm guessing that it's only a matter of time before the Russians adapt to the Storm shadow missiles as well, just like they have adapted to the Himars, Switch Blade drones and Bayraktar TB2 before that.
The war in Ukraine war shown the importance of cutting edge technology supplemented by cost effective & mass produced platforms like the Shahed and Lancet. Procuring the SU-35s was a good start for Iran's air force. A few more dozen SU-35s wouldn't hurt either and producing the SU-30 under license, preferably with technology transfers would also be a good addition to Iran's arsenal. The SU-30 would be a good workhorse in my opinion.
Near zero chance for SU-57, it’s stuck in prototype mode. It could be another 5 years before mass production or never.
SU-75 seems a more reasonable versatile fighter, looks like a stealthy F-16.
Assuming Russian can source 100% of all the components and kick start mass production then SU-75 seems like a no brain purchase for Iran. A cheaper 5th Gen fighter that can defend airspace.
As of right now it’s just speculation thought. War in Ukraine has thrown a wrench into any Russian R&D program.