What's next after restaurant-delivery apps? Everything-delivery apps!

Hungry urban-dwellers already know the drill: open your computer or an app, choose the restaurant you want food from, and get it delivered quickly. It works. So why shouldn't the same model work with everything else you want, from retail shops all around town? Between startups like TaskRabbit and PostMates, the expected expansion of AmazonFresh (the online retailer’s same-day delivery service), and other new local delivery options the on-demand delivery space is getting very crowded. WunWun is one such app that's looking to revolutionize the shopping experience in New York City with on-demand delivery from any store in your neighborhood. Pickup and delivery from any store selling generic items like food and office supplies is free. If you want something from a service shop, like your laundry, or a new set of keys, they charge $20. In moments, someone is on their way to pick up and deliver your request. Can this business model last?