https://www.cnet.com/news/iphone-xr-iphone-xc-2018-may-be-the-year-of-weird-iphone-names/

Apple may throw a wrench in its usual iPhone naming scheme by using letters (and Roman numerals) instead of numbers.

Reports say that Apple will call its iPhone X followup the "iPhone Xs", with the larger 2018 iPhone model being called the the "iPhone Xs Max" instead of using the standard "iPhone Plus" moniker.