There are three groups each with their strengths and weaknesses.
One are the carmakers, OEM’s. Take for instance CARIAD, the Volkswagen software arm. They are a TomTom partner. Their strength is sensor data. There will be 40 million Volkswagen brand cars where the front camera sends data to the servers. Their problem is that they don’t have mapping expertise. They do want to build their own services on top of a base map. For instance all charging stations that are theirs. (ionity).
Then you have tomtom. Their strength is AI and machine learning and how to fuse those vehicle sensor data in the map. Also they have a team of 1.000 mapping employees in Pune, India. Making edits every day and checking change reports with other data like sattelite imagery. Their challenge is that they need those data from car sensors (and they get them)
Then there is obviously OSM. Where the strength is the wisdom of the community. But also a weakness that people can make mistakes and from time to time vandalism happens.
In this new venture you get a best of both (or in this case 3) worlds.
The India people in Pune can do quality checks on OSM data. For instance comparing with other sources. And their tools and AI can fuse sensor data from cars of tomtom partners. Those are Volkswagen group but also Stellantis (merger of Peugeot-Citroen and Fiat-Chrysler-Jeep), Toyota and others.
The TomTom base map (lowest layar) will be provided to OSM.
Forgot to mention one thing, which is Apple. TomTom gets their probe data which helps in street geometry and traffic. With the help of OSM TomTom now has a Japan map. Very important for carmakers in Japan. Big market. Because in Japan 80% of mobile phone users are iOS users (huge iPhone marketshare) this is an opportunity to get data from many sources together. Also from Japanese carmakers like Toyota who do research with TomTom on HD maps for autonomous driving and assisted driving (ADAS).
This looks like a win-win-win for all three. Carmakers, TomTom and OSM. And a worry for Google Maps and HERE technologies.