If you hit the new limit of follow 5,000 accounts and want to add more, Twitter may allow you depending on how many people follow you.
“When you hit this limit, we’ll tell you by showing an error message in your browser. You’ll need to wait until you have more followers in order to follow more users—for example, you can’t follow 10,000 people if only 100 people follow you.”
In addition, Twitter will be monitoring and cracking down on aggressive following, as well as following and unfollowing.
The company has updated its following rules and best practices to indicate that it’s not acceptable to mass follow a large number of accounts. It is also not considered acceptable to repeatedly follow and unfollow others.
Twitter considers this type of activity to be “spam tactics”, and warns that it
This applies to all users, with some exceptions for those who wish to follow more accounts.