Overseas airbase infrastructure and political access

Do worldwide airbases and supposedly superior land-based aircraft remove the need for carriers?

No. Many runways lack the infrastructure to support advanced combat aircraft, while host-nation access can be restricted or withdrawn. A carrier brings its own secure facilities and sovereign operating authority.

Land-based aircraft are not automatically superior in every relevant respect. That argument fit the 1920s, early 1930s, and part of the Second World War better, before 2,000-horsepower engines changed the balance between carrier and land-based aircraft. Modern aircraft such as the F-35 require facilities that can maintain their stealth technology, and duplicating those facilities at every overseas runway would be expensive. A usable base also needs weapons storage, secure accommodation, and permission from the host government. Even an existing agreement leaves questions about whether that government will protect the aircraft and allow operations during a particular conflict. A carrier brings its aviation facilities under its own government's authority and can launch operations without obtaining permission to use a foreign base.