It's interesting that the article mentions Gaelic and Quechua, two languages/cultures I'm a bit familiar with. For that reason, I have to disagree with the conjecture that they'll be gone by 2030. I know both are undergoing a revival of sorts with those who speak it.
Knowing that the languages are endangered, those who still speak it are making concerted efforts to keep it alive and use it in daily life. I don't know that either will ever grow and be adopted by more speakers than they have now, but I suspect even in 25 years, there will be a core of people still speaking it similar to the number of those speaking it today.
I hope so.
"The Gaelic Language is spoken by around 86,000 individuals primarily in the North of Scotland and in the Western Isles (eg. Skye, Lewis, Harris). The vast majority of gaelic speakers are bilingual Gaelic / English. Today there are very few people who do not speak English.
"Gaelic (or Scottish Gaelic as it is sometimes known outside Scotland) has similarities to the other Celtic languages, and is particulary close to Irish (or Irish Gaelic) to the extent that a mutual understanding is possible. Another variant of Gaelic is spoken in the Isle of Man (a small tax haven between England and Ireland) called Manx Gaelic."
http://www.geo.ed.ac.uk/home/scotland/gaelic.html
Ooh, check it out...
http://www.ceantar.org/Dicts/MB2/