Lisk is a new cryptocurrency that was launched on May 24th, 2016. https://lisk.io :
Well for starters you will be able to operate a darknet market outside of tor. So you have just brought the mainstream internet users closer to a darknet market. Cryptocurrency of choice would be LSK and it is basically a decentralized network. The gov't officials would not be able to stop them. The value would increase because of the awareness just like how the silk road brought many to bitcoin in 2013 & 2014. The more bapps/dapps on the Lisk sidechains then more ways to obscure LSK transactions. https://bitcointalk.org/index.php?topic=1346646.msg15029881#msg15029881
Probably you could but nobody would use lisk because it is not liquid enough(as btc) and it is not popular enough(as btc). The more reasonably would be to build a market on ethereum blockchain because eth is the 2nd most traded cryptocurrency but still almost all the people would be loyal to bitcoins and would never use eth.
Silkroad argument is pretty lame to be honest because at the time when silkroad launched there was only bitcoin and today there are hundreds of cryptocoins/altcoins.