Maximum caps for users
The caps will be set based on the current number of users that these clients have on a multiplicative scale. So, if a client has x users as of today and that number is over 100,ooo, it can have 200% of x users maximum. This means that any client like Tweetbot or Twitterrific can only ever have a certain amount of users, period.
The maximum limit is 100,000 users, unless special permission is given by Twitter. If a client has more than 100k users currently, it can only ever grow to 200% of that. If users of the apps de-authorize their tokens for those apps, then theyre added back to that pool.
That means that no third-party client can ever have more than 100k users, unless given special permission by Twitter or it already has over 100k right now, in which case it can have double the amount it has today.
This move puts a life span on most for-pay clients, as theyll reach a point where there is no longer any reason for them to continue offering these apps for sale. Lets call it Max Reach. If youre a user of a favorite third-party client already, youre in, but those who wish to get in on one in the future will need to get cracking if they want to get in under the cap.
As far as whether developers of these clients will find it worth their while to continue supporting and updating the apps, knowing that they have a maximum growth limit, who knows.
Basically, Twitter just told all developers exactly how much money they can ever make selling a for-pay client. The future of Twitter is its official apps.