Since midway point 2015, the Bitcoin community has argued to no end about the future of the Bitcoin protocol. The core of the debate revolves around whether the software should be soft-forked or hard-forked, technical terminology relating to the way in which to implement a change to the way Bitcoin works. In this case, the particular change revolves around how much data the system can process per ten minutes, known as the block size. Many people want to increase the block size from 1MB to 2MB.
https://www.cryptocoinsnews.com/an-exodus-from-bitcoin-to-alternative-digital-currencies/
I doubt there is an "Exodus". Bitcoiners would most likely hold their BTC while investing in the other alts. Cant see someone selling all BTC to go all in to alts, but who knows.