Are there any indications that (global) English is going to split into different languages in the next hundred years?
If anything, I would expect the opposite to happen.
During the age of colonization many scholars predicted that the distances between English-speaking populations meant that by our times the average American would not be able to understand the average Australian, for example. What happened instead was the telegraph, and the telephone, and other advances in communication that kept far-flung speakers of English in constant contact with each other, thereby reinforcing the commonality of the language. Today, of course, we regularly exchange messages with people living on every continent, thanks to the Internet, which is likely to lead to regional variations either disappearing or being absorbed into worldwide English.
English will continue to evolve, and is likely to pick up qualities from places like India that have not historically contributed significantly to the development of the language before now, but I would not expect to see the English language fragment.
My money would be on English becoming more affected by places like India (and perhaps china) for everyday use as another billion english speakers come online.
Traditionally English has been very happy to absorb other language influences so I don't think there will be a formal correct English and a 'street' Indo-English in the way there was latin/vulgate.
Tok Pisin is already a descendant language of English.
In the book "The Last Lingua Franca" there was a fascinating case study of modern Tagalog (Taglish), which mixes in a lot of English, although as with all issues that aren't black and white, one could quibble if it is a form of Tagalog with English loan words, or a English dialect with Tagalog influences.
Mass media, in my opinion, is really slowing down the rate of language fragmentation compared to what it was historically.
I think it's more than just a metaphor to say languages evolve.
In that context, I would suggest the Galapagos Islands were a particularly good place for Darwin to investigate the evolution of finches.
Evolution (and more particularly speciation) occurs more often and more quickly when there's plenty of scope for populations to become disconnected.
By (more than just) analogy therefore, we can reasonably expect languages in general will become more homogeneous in the future because of increasing worldwide travel and intercommunication.
Logically, we should all be speaking Chinese in 100 years time, but because English has such a dominant position (not just on the Net), I think it will eventually become the only game in town.
I know it's always sad to lose diversity, but most Welsh people took the decision generations ago to bring their children up with English as their primary language. For the quite obvious reason that this would enhance their prospects for economic and cultural / social success.