As someone who has followed the constructed language and international auxiliary language community for a couple of decades, and as someone with an undergraduate degree in linguistics, I do not see a constructed language catching on with the mainstream public any time soon.<p>A constructed language is a language that someone sits down and creates; this is different from a natural language which just forms as people communicate with each other. There are many constructed languages: Klingon in Star Trek is an actual constructed language, as is the language the Elves spoke in The Lord of the Rings.<p>Esperanto, and Interslavic, are examples of <i>International Auxiliary Languages</i> (IAL), languages specially made to be easy to learn to facilitate international communication. We have had those languages for well over a century, and none of them have caught on.<p>The reason why an IAL has not caught on is because people are motivated to learn a language when it has prestige, not because it’s easier to learn. Right now, for better or for worse, English is that language (with all of its warts: Auxiliary words to carry tense, the rather strange tense/lax vowel distinction, etc.) right now.<p>I would love to see an IAL to catch on, but there’s a serious marketing issue, especially since a lot of people just don’t have the mind to learn a new language as an adult, no matter how easy the language is to learn.