The value of Gulden is determined by the demand for Gulden, as with gold or silver. Prices can go up or down, but the Gulden average increases. In 2016 the value of Gulden has increased by more than 100%.
Does Gulden's future matter? Its profits continue to be born. I do not have much information about it so I do not want to risk it.
Yes, but so it goes with every coin that has development. BTC more than 1000% value increase, many other coins >200% value increase... and the value increase on NLG is mostly due to BTC going up. If you look at the very long term trend line... NLG is almost bumping against it. That trend line should be somewhere around 1800 sat.
NLG biggest problem is currently the price increase of BTC... let's hope those EUR exchanges are here soon, so it can be decoupled from BTC.