Will MCO 16 ever come out

99.99% NO

Good Chess Openings Books For Beginners and Beyond...

https://www.chess.com/blog/RussBell/good-chess-openings-books-for-beginners-and-beyond

I agree with @TundraMike There will almost certainly not be a 16th edition. There is no need for it. It's meant as a reference for advanced players with little-to-no explanation of the reasoning or frequency of the moves. It's been a while since I've looked at it - I regretfully bought a copy -but I don't think they even explain how to read the complicated charts that give all the moves. The book has been completely supplanted by computer resources (e.g., opening databases).

@RussBell gives a good list of opening books, all of which would be a better purchase than MCO. If you want something comprehensive, Fundamental Chess Openings (FCO) by Paul van der Sterren is probably the single best resource.

The previous MCO books were written in the bronze age of opening theory. So much that many lines that are given in the books are no longer critical or have been rendered obsolete by modern theory, which has been completely immortalized by the accuracy of stockfish. Back then, when older MCO books were being developed, computer engines still needed their own opening books to get decent positions in many critical lines, but nowadays, Stockfish is so powerful, that it literally *creates* opening books by itself. You can just run stockfish, play a Najdorf or Botvinnik Semi-Slav or Anti-Meran, and instantly get all of the main lines outputted by the engine itself. And then you have all the chessable courses...The wide number of viable lines now, including previously "discredited" variations, would make any MCO volume extremely unwieldly, and far less useful than a much easier to access and reference megabase or opening monograph. And since people have laptops everywhere, they can just take their work with them, which makes print media (for openings, at least) extremely tedious for finding lines you need to reference.

If people wanted to just study chess in a park, with a physical set, without having to deal with lugging a phone or laptop around, they would be far better off having print media like Dvoretsky books, or Think Like a Grandmaster with them, and some Informants or NIC to work on analyzing complex positions, rather than any sort of opening books.

Y'all just saved me from a headache xd also tysmmmm @RussBell , @goodspellr and @ike_Miller for the book recommendations and explanation! My 550 elo brain is grateful!