expect to break a ball joint or two.
The only mechanical failures I've ever noticed at an autocross, seem to always be due to:
1) A car that was modified with a "grassroots design" part (i.e. homebuilt, low end aftermarket), and the design just flat out wasn't strong enough
2) A part that was already broken before the event, and just finally reached the catastrophic failure point at the event (i.e. the part was just as likely to fail on the drive to or from the event as it was at the event).
In 10 years of autocrossing, I've never seen a stock car in reasonably good condition have any OEM part break. Not going to say it can't happen, or even hasn't happened already somewhere else... but it's just incredibly unlikely to happen. Autocross certainly does put increased loads through the suspension - but I would argue that hitting a pot hole on the street puts MORE stress through the suspension than autocross - and it's very rare to find a pot hole at an autocross event (unless you're driving a kart, in which case they seem to be everywhere).
For a stock DD car, likely the only long term effects you'll notice is increased wear & tear on things like tires and brake pads - things that would wear out on the street as well, but you'll just notice that you have to replace them a little sooner than normal.