The retirement announcement does not eliminated the use of it or the need for it. It was retired because the test equipment didn't exist any more to prove compliance.
Also considered throughout 15 years of debate on the issue was the fact that many manufacturers have gone with their own spec to keep people from using GL-5, or come out with their own "Synchromesh" or manual transmission fluid. Each actually would meet the GL-4 EP requirements (but can't be proven).
I agree with Chevron's dissenting opinion that the whole transmission/differential classification needs to be revamped.
Yes, officially GL-6 has been retired for the same reason, but some brands still spec it for their differentials.