According to a reliable source, Apple is developing a larger MacBook Air to complement this year's 13-inch model. The report tallies with one published last year by Mark Gurman and would mark a signficant change for the MacBook Air series.
https://www.notebookcheck.net/Apple-rumoured-to-have-a-larger-MacBook-Air-in-the-works-for-next-year.609788.0.html