While I share most of your vision, I don't agree with the PND. Even the remotest corners of the world have mobile phones, and as all mobile phones have navigation, there will be no need for PND hardware.
Similarly, every single car (except the cheapest ones without power windows) will have in-dash navigation.
By 2015, any navigation screens less than 7 inches (eg anything not-in-dash) will be outlawed, as people start realizing just how unsafe they really are. Right now, the added safety of "knowing where you're going" is masking the dangerous effect of sub-7-inch PND screens. As studies come out showing large-screen vs small-screen safety records, the truth will become clear and politicians will react.
So I feel the PND will virtually "disappear" from a sales standpoint. And that's not the distant future, my date is 1/1/2013.
When it comes to maps, I don't believe in pure cloud. There is immense costs in transmission anywhere outside metro areas, so the world will move to Ovi-style on-demand plus pre-downloaded mapping. Crowdsourcing is here to stay, and as "false mapshares" get legally regulated like graffiti, the cost of mapping will continue to decrease.
I don't believe there's money in location-based marketing. There will be ITU standards of pushing location-based ads to devices near you and the costs will plummet, so storefronts will be able to bypass the advertising likes of Google. Location-based intermediaries are like the 1980's travel agents, making sense of a confusing market, but have no valuable role once technology replaces them. And I predict this will happen before location-based investors even see a cent of positive ROI. Someone will do to Google what Google did to Tomtom, offer the perfect customer eyeball for free, in exchange for something unrelated like the transaction checkout commission.
The future of Garmin & Tomtom? Well there are separate specialties within navigation: antenna, input interface, output interface, map(including traffic), and routing. Antenna, map, and routing are just about perfect, so I see no further R&D there, just licensing of existing patents until they expire. Output interface is the move to in-dash/augmented reality for the car, and mobile phone for pedestrian. And input interface has the most innovation.
So Tomtom will ride its patents out licensing it's map/traffic/routing IP (either independently or via acquisition). It's output interface is a leader in in-dash, and may soon build scale that creates real barriers to competition.
Google, Apple, and someone else (maybe Adobe) will end up owning the smartphone output interface. Sirf, and Global Locate will own antennas.
The only real innovation left is in input interface, it's the worst part of today's navigation. Who knows, maybe someone will come out of nowhere here, like IBM Watson.
Garmin's not a leader in any of this. It led the "all-in-one" PND, but with the PNDs death all it has left is its stellar brand name. It has to figure out its new future soon, though its cash buys Garmin time. Perhaps someone like Nokia will buy them, to gain better USA brand recognition.