I stumbled on this video yesterday and it kind of confirmed my fears of the career adhering too strictly to the succession of the different tiers, which makes it more linear than I expected and not really realistic. Real drivers don't necessarily go through all different tiers. For instance in the below video, the player won the Kart Series and now has the option of running another season in Karts, or choose between two offers in Super Karts. I don't think that Super Karts are a true to life step up into the higher classes. Maybe only for a small minority.
What I was hoping for is a more open career, where the offers you'll get are depending on how well you did. Suppose that you completely aced Karting, you'd expect offers from Formula Rookie or even Formula Gulf or Formula C. Or maybe an offer from the lowest Prototype series. That would make the career look less predicatable , more realistic , more interesting and more fun.
Now it looks like you can only progress into the very next tier, or change to other series in the same tier. In that sense it wouldn't be much different from some other games we've seen in the past (except then for the option of choosing your starting point).
Or am I completely wrong, and does the below video not do justice to the depth of the career mode at all?