I think a lot of third parties are already working on and delivering payment systems like this for Bitcoin.
I think with BTSX the premise is that people want the advantages of storing value in a decentralised way but not the volatility of Bitcoin. (Bitcoin also isn't very decentralised.)
If that premise is true, then more and more people will store some of their value in BitUSD, BitGold etc. As this amount gets bigger it will appeal more to retailers and third parties to interact with the BTSX customer base. Retailers will be very quick to adopt it, as with their tight margins they will really value BitAssets too. This increased utility will then attract more users and so on..
Anyway I think the development team just needs to focus on delivering a robust, decentralised (Delegates + developers) BitAsset system and the rest will build up around BTSX quickly.