That would be great except Proprietary Data/Imagery and the fact that people want someone that can be held "semi" liable for the product since it could be a matter of life and death should the information provided by the app be wrong. As much as I love the idea of a decentralized map the problem of verifying and validating changes and general data is an enormous undertaking, the benefits of course being censorship proof maps but the cost being very high. Speaking of high, with all the recent drones there could be a network to capture imagery and splice together the data, and another idea is to do what Google did and use scan the terrain with a laser, getting topographical 3D data, considering that it could be possible to do by most anyone that might prove to be quite lucrative, especially if the people are rewarded for capturing the data.