Yes, but. . . . And, if just one language survives, barring major geopolitical upheaval with a country that speaks some other language conquering the world militarily, religiously or otherwise (a la the Firefly universe where the Chinese become dominant at some point with linguistic consequences), it will be English.
Honestly, by 2500, I think it would be more likely that we would be down to a dozen or so major languages with languages like Finnish, Basque, Catalan, Hungarian, Yoruba, many of the official languages of India, Mongolian, and similar currently non-endangered languages in an endangered or even moribund status, it would probably take longer to get down to just one dominant language even though the writing would be on the wall. But, it wouldn't take a huge push of some sort, such as a single global college entrance exam administered only in English, to tip the balance.
We already use English as a common global language in fields like international air travel and scientific publication. Countries from Japan to Sweden to Finland to India make learning English as much of a requirement for their elites as learning Latin or French used to be in much of the world.
English, French, Spanish, Arabic, or Chinese is spoken to some extent almost everywhere in addition to other languages. The main national languages of North and South America and Australia are English, Spanish, Portugese and French (and French is in peril as people in Quebec have to learn English as a second language to function in their larger country). English is more unifying in India than Hindi. Much of Africa uses French or Arabic or English as a lingua franca in addition to local languages which are fading because they don't have socioeconomic prestige or a wide enough community of people who speak them. China and many of its expatriot communities can speak some version of Chinese. Arabic is spoken in some form or another across the Islamic world and in many places has supplanted previous local languages almost entirely.
More people in China learn English than visa versa, first of all because Chinese is not a single spoken language even though there is unity in Chinese characters, and secondly because English has a global spread while many Chinese languages are spoken only in regions within China.
There is a strong tendency for any top level sovereign government to make a language dominant and that dominance in positions of power leads people to adopt it.
The source of the prediction of the death of up to 90% of all
languages by the end of the 21st century is a 01992 paper titled The
World's Languages in Crisis by Michael Krauss, professor emeritus of
the University of Alaska Fairbanks and expert on the indigenous
Alaskan language Eyak, whose last native speaker passed away in 02008.
Krauss arrived at this estimate based on the best available sources at
that time.
Today 457 or 9.2% of the living languages have fewer than 10 speakers
and are very likely to die out soon, if no revitalization efforts are
made. 639 of the languages known to have existed are already extinct –
10% of all languages.
Moreover, we now know that since 1960 we have lost as many as 28
entire language families. . . . .
We know of a hundred language families that have gone extinct over the
course of history - 24% of the world's linguistic diversity. But the
fact that 28 of them have gone extinct over the relatively short time
span of the last 50 years is symptomatic of the accelerated rate of
language loss we are experiencing in recent times.
[There are] 3,176 endangered languages.
From here.
According to a September 18, 2007 article in the New York Times reporting on National Geographic study:
Of the estimated 7,000 languages spoken in the world today, linguists
say, nearly half are in danger of extinction and are likely to
disappear in this century. In fact, they are now falling out of use at
a rate of about one every two weeks.
Some endangered languages vanish in an instant, at the death of the
sole surviving speaker. Others are lost gradually in bilingual
cultures, as indigenous tongues are overwhelmed by the dominant
language at school, in the marketplace and on television.
New research, reported today, has identified the five regions of the
world where languages are disappearing most rapidly. The “hot spots”
of imminent language extinctions are: Northern Australia, Central
South America, North America’s upper Pacific coastal zone, Eastern
Siberia and Oklahoma and Southwest United States. All of the areas are
occupied by aboriginal people speaking diverse languages, but in
decreasing numbers.
The study was based on field research and data analysis supported by
the National Geographic Society and the Living Tongues Institute for
Endangered Languages, an organization for the documentation,
revitalization and maintenance of languages at risk. The findings are
described in the October issue of National Geographic magazine and at
www.languagehotspots.org.
Languages are like operating systems, compatibility is key to their value and a perfectly good language is useless if no enough other people speak it. And other languages can be purged so quickly because language survival happens in more or less the same way for all similarly situated smaller languages in parallel. The smaller, indigeneous languages that are not official languages of any states will go first, then the smaller languages that are part of states as everyone in those countries learns to speak a common language to survive in a small world connected global economy, and finally the bigger languages will grow less popular as people see less value in passing them onto their children as native languages.
Now for the "but". If a single clearly identifiable world language, or at least a mere handful of remaining living languages were spoken, wouldn't necessarily mean the total extinction of other languages even if they were rarely used in the way it did for languages that were never committed to writing.
Sumerian survived for centuries as a liturgical language in the Akkadian empire which was linguistically Semitic. Hebrew and Latin and Coptic likewise survived at liturgical languages long after they ceased to be languages of daily life and have even been revived in Israel and Vatican City respectively, as living languages. There are still people who can read Egyptian hieroglyphics, ancient Mayan writing, Sanskrit, and Tocharian, even though the surviving descendants of these languages are much different today. Any language committed to writing and recorded in video will survive as an esoteric means of academics, spiritualists and hobbyists to commuicate as a secondary language.