True---we will never know what happens till it actually happens. So guessing is difficult.
However, the RISK is much higher at EK than many others. Maybe upgrades keep going at 4 years (doubtful in my opinion) and maybe they increase.
This 'risk' is lower at other Gulf airlines and so if a person has a choice EK should no longer be on the top of the list. Your odds are better for a quick upgrade at the other airlines.