I wouldn't assume such things. I remember having to go buy a USB-A to lightning cable after my first iPhone purchase, hoping to use it with a "fast charger" I received with my OnePlus and the iPhone not charging at the maximum speeds it was supposed to. So, naturally, I had to get a new charger to go along with it. Few months later, I got the iPad Pro and it comes with a USB-C to USB-C cable and well, I don't have a charger that works with it either and had to go out and buy another one.
Fact of the matter is that even if interfaces look the same in the next few years, they'll continue to evolve, get better characteristics like faster charging speeds. If they're advertising all this as features of the product, I expect it to come with the product.
And even if none of these were true and I had the right charger already with me, I'd still want that charger in the box so that I can charge multiple devices at a time and not think whether this charger has the best possible charging speeds and characteristics to support the device I'm using.