Companies will increasingly not ship frontends anymore, maybe just themed components that most users will ignore. "Pages" naturally become synthetic amalgamations of the various things you are interested in from various sources. Your preferred UI/UX comes for free courtesy of your LLM intermediary.
Everything is an API. Regulation will probably be needed to enforce this on the data access side given the incentives for companies to resist despite the benefit to the consumer. A relatively easy solution is to make it part of the requirements to take payments online, which is already highly regulated. The goal would be that essentially to operate anything approaching e-commerce online you must allow consumer AI intermediaries sufficient access that they could independently construct whatever your current frontend is from the publicly available API/MCP endpoints.
The tricky part of engineering around privacy/personas, account creation, etc. will be relatively easy following such state intervention. Take payments - virtual credit cards are already a useful way to protect data and mitigate risks when dealing with multiple vendors. This sort of API is a natural fit for a world in which companies are not allowed to box you into their horrible UIs, most of which are simply lazy attempts at copying the most profitable anti patterns of their competitors. Let your personal agent generate a unique card for each vendor behind the scenes. Why should you have to care?
How much better the internet would be if every UI/UX was in a meaningful sense, your own.