Hard Fork Conspiracy TreacherousBitcoin Classic and BitcoinXT (meaning in this case the new resulting currency itself rather than the software) would likely be considered by FinCEN to be a new convertible virtual currency. FinCEN has made it clear that a creator of such convertible virtual currency, who issues such currency in order to sell those units for either real currency or its equivalent (including presumably an exchange with current bitcoin), is deemed to be a money transmitter.
http://www.riddellwilliams.com/blog/articles/post/hard-fork-conspiracy-treacherous I would suggest before reaching any conclusions on this to read the actual FinCEN guidance on the subject:
https://www.fincen.gov/statutes_regs/guidance/html/FIN-2013-G001.htmlFurther clarification for mining
https://www.fincen.gov/news_room/rp/rulings/pdf/FIN-2014-R001.pdfIn article the author does not reference the guidance or the difference between a de-centralized virtual currency and a centralized virtual currency. He also does not provide any justification for his implicit claim that Bitcoin Classic and Bitcoin XT are centralized virtual currencies as per the FinCEN guidance while Bitcoin Core is not.