What Happens to the Equestrians in the Roman Empire?

In the third century a d. men who have worked their way up from the ranks of the army promoted to equestrian officer posts without having been equestrians first. Several of these men then go on to become roman emperors. What eventually happens under the constantinian emperors is that the numbers of senators are increased. So for the first time, you have more than 600 senators. But it doesn't really change the structure of the roman state in that aristocrats are always ordered into hierarchical groups. And that's because aristocrats need to feel that they're better than other aristocrats as well.