When they talk about iPads replacing laptops in terms of using it for things like email, web browsing, social media, basic productivity, then duh - of course. That's just tablets doing exactly what tablets were designed to do. It's just the logical evolution of how people do basic computing tasks now, so of course people now do less of that on a traditional laptop.
When they talk about iPads replacing ALL of a laptop's capabilities, that's something entirely different though. There are too many capabilities, ports, and management capabilities missing to replace how laptops are used for more powerful productivity tasks. That is, after all, why Apple just released yet again new MacBooks. They even acknowledge the iPads limitations in this regard.