I think a huge use for Constellation would be a tip app or some app or dapp able to send micropayments to someone. You know how everyone always leaves their ETH and BTC addresses after an article or website what have you? Think if it was easy to actually tip that person, and CHEAP. Say I want to tip someone 1$ in BTC, its going to end up costing me 2$ just to do that. With Constellation, that will be possible!
Agree. Micro-transactions are a huge opportunity(lol, the irony ). I was listening to someone recently who was building something in this space. The change you get from Starbucks or say McD, will be transferred to a digital wallet, which allows you to cash out in a crypto of your choice, when you reach a certain amount in USD.