How long would a well taken care of Focus RS last?

I’m looking for one owner somewhat low mile examples but I’d like to know roughly at what mileage issues would start to pop up.

I have no plans to modify it for power, and I plan to daily it. Should I avoid high mileage ones? I see a lot popping up for ~80k miles.

I also see that 2018 RSs are viewed differently to 2016s and 2017s. Should I only look for 2018s?

Thanks!