I think emoji can be considered a language - or part of one that’s not yet complete. Emoji originated in Japan, as a parallel to Kanji, which incorporate chinese-origin characters as a key part of japanese language. Chinese characters also began as ideographs (and some still are). Of course there are now many tens of thousands of chinese characters - a far greater set than current emoji, but it’s not implausible that emoji could develop in a similar way, combining radicals to derive more abstract concepts, and with a similar grammar structure (chinese grammar is relatively simple, and does not need to transform the characters).
So emoji could evolve to an ‘international chinese’, more colorful, but both made convenient by computer auto-typing. Anyone else remember how back in the 1980s, western experts predicted chinese characters would die, because they were hard to select with mechanical typewriters (meanwhile japanese invented fax machines to cope with this problem)? Times change, languages evolve.
Having said that, for emojis to develop further, the process for adding new ones to the list needs to evolve too - much broader range of priorities and participation.

Emoji are pictographs, aren’t they?