15,000 miles - what needs to be replaced

So yesterday I cracked 15,000 miles since 10/04 on my bike. Other then the chain, cassette, and other consumable parts all are original: cranks, bottom bracket, chain rings, derailers etc - frame was replaced due to a crack 3 weeks ago.

What components should I think about replacing based on “rules of thumb”. In general I have no complaints about the ride of the bike or it’s performance, I just don’t want to be in a race and have something decide to go - or be losing out on gobs of power because of worn out parts.

IMO, the rules of thumb is to replace the parts that are too worn to work well. Most parts can last a long time. My 21-year-old bike with Dura-Ace has ~100,000 miles on it and still has most of the original parts on it. I think the only things I’ve had to replace are chain, freewheel cogs, cables, bar tape, rim tape, and tires and tubes. I did replace the brake levers, but only because I couldn’t find replacement hoods that would fit.