There has been talk of a potential BTC ETF in the works. Would this compete with BTS? Is this seen as a major threat to the viability of BTS?
BTC ETF is just a way for ordinary investors who don't want to deal with the technicalities of Bitcoin own a piece of the Bitcoin pie.
BTS is a trading platform that allows, through a prediction marketplace, to trade just about anything, including, bitBTC.
I don't see how the former will threaten the latter.