I said everything will be expensive, but the touchbar breaking in the first place is probably less likely than the other mechanical parts.
In this day and age, any life you get out of a laptop over 3 years is bonus time. Not saying you shouldn't expect a computer to still work after 3 years, but factoring the obsolescence, wear and tear, resulting depreciation, it wouldn't be unreasonable to expect to buy a replacement anytime after 3 years. This varies of course, so I hope no one jumps down my throat claiming they always use computers for 6 years. There's a good financial reason extended warranties don't go much past a certain point, the expectation of major repairs on older machines combined with the lower value makes it uneconomical. TLDR, you are worrying too much about this and going into what-if scenarios.