Credible Sport Project: Is it possible to revive the idea with modern avionics?
It wasn't a lack of technology. The technology to automatically fire the rockets is not actually very complicated: a radar altimeter, airspeed data and maybe input from the landing gear load sensors hooked up to a simple computer. All of that existed back then, and the rocket system was in fact computerized:


  The Lockheed test crew then assessed that the computer used to command
  the firing of the rockets during the landing sequence needed further
  calibration, and elected to manually input commands.


So the plan was to use computer control, but it needed more development than they had time for - as were in a very big hurry they decided to do it by hand. 

If they'd had more time to adjust things they no doubt would have succeeded with the technology of the time. The reason that the project was canceled was not a lack of technology but that the hostages were released. 

In reality the plan to use rockets to slow down the airplane so quickly was extremely risky, and if it went wrong the US military would have had their best special forces units stuck in the middle of Tehran! I personally don't think this would have gone ahead even if the tests had been successful. The fact that they continued to develop the concept into the MC-130 Combat Talon II without the rockets indicates to me that the military thought the braking rockets part of it wasn't worth it. 

So no, modern avionics really would have nothing to do with it.