For more than 100 cars (if unique) they are likely counting their full 2016 roadmap, unless they've made some more third party mod deals. They say 20 track configurations which is about what they already have.
16 car grid makes sense at current AI state, even more so that it must be some work for a small team to optimize the game for two other platforms.
These next months will be interesting though, as an early adopter the development progress has been slow outside of paid car expansions that amount to full price already.
I just hope they sell well enough to travel and scan more tracks, I can live with the game being a hotlap box.