Yes. ZCash can become more valuable than what it is right now over the long term. It has been slow in many things such as development, and price rise, but it has managed to remain stable in the cryptocurrency markets. Sometimes being slow is the best way to go towards ensuring a safe trajectory of any cryptocurrency project.
I've been closely watching ZEC over the past months since it was launched, and it has gone a long way to become what it is right now. Of course, it needs more innovation, as it lacks a user-friendly wallet which limits its ability to become used in the mainstream world. ZCash has all the goodies of Bitcoin with added privacy, so it has a huge potential to become one of the best altcoins in existence.
Besides that, ZCash has managed to gather the attention of other altcoins, as new forks have emerged with ZEC's privacy technology and some extra features. ZClassic, Zcoin, Komodo, Kurrent, and most recently, PIVX have all adopted Zero-Knowledge Proofs making them extremely anonymous cryptocurrencies (if users make use of their optional privacy features)
Nevertheless, now that cryptocurrency prices have started to decline, it would be best to grab a stake of ZCash while its cheap. Just my opinion