One phenomenon that we will see some more examples of in coming years is "language rebirth". It has happened with Hebrew and Gaelic. Godwilling, Coptic will follow suit. As many languages die out, a few will reignite somehow, someway. Plus, with the added "virtual seedbank" of texts and recordings and (improving) linguistic methods of transcription and analysis, it will be easier to do so for those so motivated in the future.
Otherwise, I think the Internet and education are forces that may tend to concretize language, or give room for more variation to exist simultaneously within a language continuum, but actually prevent those changes from actually coalescing enough to make actual linguistic mitosis into daughter languages. We're just too much in contact with one another nowadays.
moribund = little motivation for new speakers to acquire, structures not innovating and fossilized, loss of prestige & too much competition from other languages
extinct = kaput (may or
may not have a written/textual legacy)
I think globalisation will kill off many of the smaller languages but I'm skeptical it will inhibit dialectal development. Many people on my Facebook friend list write in our regional slang, for example, 'youse' is used, it doesn't seem like it is slowing it down, only providing a new platform for people to communicate in their own regional dialects, it actually reinforces a dialect in a way. This is only my opinion and from my knowledge of course, I couldn't comment about anywhere else.
This may speak to the argument that Internet slows down language/dialect death.
15-20 years ago, almost everyone on the block I live on would have used the same "youse" pronoun.
Now, that pronoun is no longer uttered. I don't even "youse" it.
Perhaps it's because those who speak it still have shifted to another area. I think education drummed it out of a lot of people's speech. That, and then a whole other generation started growing up hearing the use of "y'all" as prestigious, mainly in hip-hop music, but from other sources as well. Once in a while, in a heated argument, I may hear someone say "Youse can't tell me....." but that's not so common. The "youse"; not the arguing.