GTAForums administrator named uNi commented on the rumors regarding the possible GTA 6 announcement. According to him, the original hype was something related to GTA 6 happening in March, but not exactly on the 25th, as many expected.
The mysterious Scottish user gonnaenodaethat didn't actually mention any date. He only mentioned 0320. This can be interpreted as March 2020, which was confirmed by the GTAForums administrator (who is also from Scotland, by the way).
So there are still 6 days left. The rumor about March 25 came from another anonymous leak on 4Chan, which now we know was fake.
At the same time, gonnaenodaethat claims he will ban himself if nothing happens in March, and asks people to have faith.
We should also note that the first GTA 4 trailer was released on March 29 back in 2007. But people couldn't watch it for a while due to a huge server overload. We hope this won't repeat with GTA 6.