I have a Macbook since 2011. 5 years is not particularly long, but I'm not sure what bearing that has on the subject.
Interestingly enough, I never bought an adapter for any laptop I've ever had, before the Macbook (and I had a few Sony first, then ThinkPads). Even with my existing Macbook, I didn't feel the need to immediately go and buy dongles for it. Since it has USB-A, it covers most day-to-day uses.
I've never had the experience of buying adapters towards the end-of-life of PCs. Can't even think of an example. In fact my last ThinkPad, bought in 2008, had ports that are still perfectly usable today.
I've already ordered the new 15" (I need the fastest one in terms of CPU and SSD), but I'm thinking that in the lifetime of this new machine I'll probably never plug anything natively USB-C into it except perhaps my Android phone.
The reason for this is that USB-C is like 4k BluRay: nice, but completely unnecessary. Unlike the original USB, which solved a real problem and unified many ports into one (serial, parallel, PS/2), USB-C is just an improvement. Most people just don't need 40Gbps TB3 daisy-chain capabilities. They need to plug in their mouse, keyboard and monitor, and perhaps a USB drive, which is probably USB-A, like the rest of their stuff.