The interesting article kindly submitted here reports:
"His finding: Less than five percent of languages in use now exist online.
"Much of that gap can be attributed to the fact that the languages people use vary widely, in terms of scale and geography."
Well, yes, little-used languages, and especially languages with small numbers of speakers that are also geographically limited to places with limited provision of the Internet, will not likely be used on the Internet. Whether or not such languages are still used in family life or for local community interaction is a distinct issue.
I am multilingual, as disclosed on my Hacker News user profile. The number of languages in regular use on the Internet is more than any one person can learn in a lifetime (most claims of one individual being able to speak dozens of languages fluently are very badly exaggerated) and every one of those languages, from multiple language families, is very likely to stay alive for a long time. A person who speaks more than one language, as I do, can choose to use different languages in different circumstances, as I do. Indeed, for many multilingual people, "code-switching" is part of signaling a switch to a different tone in conversation (say, from serious to humorous, or the other way around) or signaling "social register" (whether the person you are speaking to is being treated with friendly intimacy or with distant deference).
So I am not worried about this, on the whole. Other comments here posted before mine talk about the strong version of the linguistic relativity hypothesis (that "language shapes thought") but the strong version of that hypothesis is certainly untrue. (For one thing, human beings don't always think in language, but often also in pictures or in music.) Diversity in language will not go away because of the Internet. If diversity in language diminishes a little bit, while humankind enjoys better health, longer lifespans,[1] and other benefits of increasing worldwide prosperity, I will feel wistful about that, because I am curious about all world languages, but people should be at liberty to decide what languages they use, and when.
[1] http://www.scientificamerican.com/article.cfm?id=longevity-w...