Getting Merchants to accept Bitcoin is difficult enough , adopting an alt currency that no one has heard of is a whole new level of difficulty. Most merchants think that it isn't worth their time integrating Bitcoin for the potential 400k- 1 million Bitcoin regular users(not total investors). NxT users are far more speculative than Bitcoin right now thus there may only be a handful of potential clients willing to spend NxT worldwide.
For now, you are right. But my theory is that a PoS coin will seriously threat Bitcoin's leadership in the cryptocurrency world in the coming years. Bitcoin's transaction costs are pretty high because of mining, only that for now the price boom has "hidden" this fact. Now probably we are seeing the actual bear market as a consequence of the freshly mined coins being sold. Nxt and other PoS coins don't have this problem and thus can offer smaller transaction costs.