I was skeptical about the date being pushed back but it looks like a recent report from LEGO directly (about their revenue and trading) gives the date as 2018 too.
Source: http://cphpost.dk/news/business/optimistic-about-2016.htmlLegoland thriving
Legoland parks around the world are thriving, according to its 2016 interims. Revenue increased 11.1 percent compared to 2015.
There are currently six Legoland parks around the world, including the original one in Billund, with three more on the way in Dubai (opens 2016), Japan (2017) and South Korea (2018).
Its owner Merlin Entertainment operates over 100 attractions in 23 countries, including Sea Life aquariums, the Alton Towers themepark and the Madame Tussauds museums.