At this time, very few people understand the potential utility Tauchain can have. Agoras will only be an "application" on Tauchain but it will be built by Ohad and supported by many of the same people who will be building Tauchain. So the network effect will likely exist for Agoras.

If Tauchain for some reason does not get built then neither will Agoras but if it Tauchain does get built there is a strong possibility that somebody associated with Tauchain will build Agoras even if Ohad doesn't. Still at the end of the day owning Agoras tokens is putting your trust in Ohad because he is the only person who can bootstrap Tauchain. Once Tauchain is bootstrapped then Agoras monetizes it and applies the business/market aspects.