That would be one possible dystopia, but I think we actually are going to dodge it.
Smart, on device agents that are aligned with a user's interests will be able to act as the "walled garden" the user needs. In fact, this future is anti-dysopian, because the agent will not care about existing walled gardens and digital fiefdoms, and to the extent that it's using them it's going to deprive them of ad revenue, and they'll have to sit and take it because being agent unfriendly will be a death sentence for a business.
Smart, on device agents that are aligned with a user's interests will be able to act as the "walled garden" the user needs. In fact, this future is anti-dysopian, because the agent will not care about existing walled gardens and digital fiefdoms, and to the extent that it's using them it's going to deprive them of ad revenue, and they'll have to sit and take it because being agent unfriendly will be a death sentence for a business.