This is going to take a long while to kick in. Firewall is pretty pointless on the current configurations, as there are too many places to jack into. They will need to replace or encrypt the can bus itself, which would take years to agree on a standard. It would have a huge knock on effect on the after-care for vehicles and after market parts. Theres always going to be certain areas that the have to leave open on the OBD side also, for example emissions and diagnostics data otherwise half the world would grind to a hault. Its a interesting problem, id expect to see alot of core engine ECU's go encrypted perhaps with a ECU dedicated to OBD / Diagnostics though a firewalled type of connection. There are some interesting draft proposals kicking about for exactly this. I guess the more we move towards automated driverless machines, the greater the need for locking down the data bus is going to be.