AI improvements (even the old hermit who lives in the black wood knows thats going to happen)
New pitstops ! the AI will have to pit, Scawen won't want to work on the AI again for a long while
(think of all those poor suckers who have spent hours training them only for them to be reset every time there is an update!), so he will want the pitting system to be fully up to date - future changes would mean more work on AI
Improvements to existing tracks and cars lots of stuff has probably been done by Eric (assuming hes not just working on S3 content) that has been waiting for an incompatible patch... gfx, some layout tweaks, South City... interiors. There are also likely to be changes to some cars to improve class balancing...
Tyre physics big improvements ? probably not. lots of small tweaks to hone the existing system ? very likely.
Improved Aero hmm maybe but who knows
More extensive damage modelling quite likely I think - again down to AI - if stuff like aero damage is introduced at a later date, then AI would not know how to handle it forcing another AI re-write.
I suppose Scawen could give AI knowledge of future stuff that isn't in the game yet, but to do so he would have to have a pretty good idea of how it would function and how he would implement it... maybe he will just have a scriptable AI that can be easily updated to handle new features?
Chassis flex modeling Scawen adds chassis flex modeling to the physics and gives us a go-kart for Christmas - unlikely, but it would be a
very nice Christmas surprise