Honda vezel is still 3 year old (2013 to date) so there is still some time before people start reporting hybrid battery issues ( i hope not). Honda japan is offering 100,000 km or 5 years which ever comes first hybrid system warranty. Use google chrome and use the translate option and see below link.
http://customer.honda.co.jp/faq2/userqa.do?user=customer&faq=faq_auto&id=66802&parent=60107
This does not mean that this is the life of the hybrid system or battery. Many factors, but depends primarily on two things,
1) Environment Temperature
2) Usage (%age of city and highway driving).
As far as battery replacement is concerned, each hybrid battery is made out of many cells.Please see below attached link as it has pictures of what a hybrid battery looks like and some estimation of price. A low cost method is to open up the hybrid battery check individual cells for voltage and replace the faulty cells rather than changing the whole battery which could be quite expensive 3000 to 6000 USD. You can find many videos on youtube for hybrid battery repairs (cell check & replacement) for toyota prius to give you some perspective..
http://www.hevshop.com/tips-on-battery-conditioning
