Ground transportation of the road variety in the travel industry was once dominated by car rental and highly regulated taxi services.
The two operated pretty independently and had their respective markets sewn up through a combination of partnerships with airports, airlines, hotels and intermediaries.
We all know what happened next.
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The likes of Lyft, Uber and their kin around the world (Grab in Asia, for example), like Airbnb in the private accommodation sector, arrived on the scene in a blaze of publicity, controversy and enthusiasm by users.
Their models worked because customers (both locals and travelers) liked the flexibility of the actual product and found that the ease of use made available through technology (essentially, apps) chimed well with their new, always-connected lifestyles.
Ride-hailing services - and, to a lesser extent, car-sharing - have eroded both the city taxi business and the rental market, primarily through a combination of their quick and easy availability, and cost-effectiveness.
Car rental brands, similar to some hotel groups, have seen the changes in the market and shifted both their marketing strategies and also, in some cases, tweaked their wider business models and developed services that include new forms of ground transportation.
In some respects, as new services have arrived on the scene, all the various strands of the road transportation sector market have the opportunity to continue growing - there is no sense that any particular element is going to go out of business, simply due to the fact that the volume of travelers using their services will continue to climb.
Yet, in spite of the fairly comfortable way the market has settled down (especially now that many of the regulatory issues have largely dissipated), new brands and old are on the verge some significant changes ahead.
Autonomous vehicles have shifted significantly from being the dreams of sci-fi writers to becoming a reality.
Pilot programs are progressing (sometimes smoothly, sometimes not) in destinations around the world, and the impact on the wider travel industry could be huge.
Most of the providers of car services, whether they be rental, sharing or hailing brands, have this technological change on their agenda.
Automotive manufacturers are also waking up to what is expected to be a major overhaul of the vehicle market over the course of the next 10 years.
These changes will have an effect on partnerships in the sector, how travelers (and locals) consider their options for getting around, and plenty more.
And, again, new players are likely to emerge that think about ground transportation in an entirely new way.
One of those is that giant of the tech world: Google.
It, like other consumer brands, wants a piece of the action and has the technical prowess, brand and enthusiasm to challenge preconceived ideas of how ground transportation should work.
Less than half a decade ago, a brand such as Google entering the ground transportation sector would've probably been framed around discussions about metasearch for car rental companies.
This is no longer the case - and every player in the sector should be figuring out how they will continue or develop their role in the future.
Issues for John Zimmer and Lyft
Some key areas for discussion at The Phocuswright Conference: