[dragonwriter]

> Before long, Hollywood is going to have to decide whether to continue using Roman numerals for sequels, or switch to Arabic numerals.

They’ve already decided: “whatever we feel like for the film in question"

> but when in the modern age when your new movie is “Ant-Man and The Avengers CCXCIV” it gets a little ridiculous.

None of the Marvel films have used roman numerals, and, IIRC, in the MCU only the Iron Man films and the Guardians of the Galaxy films have used numbers (and Deadpool, which wasn’t really MCU until the next one, also uses numbers) outside of early working titles. Most of the other “series” within the MCU (Thor, Avengers, Captain America, Doctor Strange, Black Panther) have used subtitles after the first (or in the case of Ant-Man, used a longer main title for the second, and a subtitle to that for the third).