I don't think new bots is necessarily needed. They follow a pre-set race line which is available on every track so theoretically you can just trace a new line based on a very fast human driver. Look at the WR records, they are pretty insane as it is.
But you bring up something that machine learning can do which is adapting to different setups and learning their limits. Considering the Ai can run a variety of setups provided by the player and some setups allow for later braking or turn-in etc.
But I think the Ai is challenging currently. Not everyone may agree, but in that case just handicap yourself with intake restriction or a lower performance setup.