No two cities are the same and ecosystems are already (or have already) built up around the needs of individual cities. There is no point investing in a route planning application if everyone already uses services like Transit or Citymapper, because there is very little chance the app you launch will provide a better service than they do, they already have high usage within cities and changing people’s habits is extremely difficult.
The answer is not to replace them – but link to them.
By integrating and linking apps and services within a city ecosystem you are able to get the best service available and connect them together. This has the added benefit of not locking you in to one supplier, providing flexibly and the ability to add services as required.