Let's be absolutely clear. Essentially *every* building, whether residential, enterprise office, public venue or industrial, will need good WiFi coverage, increasingly based on #WiFi6.
Most laptops, TVs, screens, voice assistants, tablets, consumer appliances & other non-smartphone devices will be WiFi-only. Only a handful will have cellular radios too - the economics & manufacturing/distribution complexities don't work for including 5G as a default in most electronic products.
Almost every building will *also* need decent indoor public 4G/5G broadband coverage, especially for employees' and visitors' phones. In most cases this will need to cover all major MNOs' networks, as well as public safety systems such as critical-communications LTE. (Wi-Fi Calling doesn't work ubiquitously on all phones / mobile networks on enterprise Wi-Fi, so there will always need to be a cellular network for reliable basic telephony).
The main competition for indoor 5G is actually indoor 4G, not WiFi for which there is only a narrow overlap in use cases. WiFi will almost always be needed as well as cellular, with very rare examples where it's absent - for instance outdoors on campus sites.
If you’d like more details on this topic & my deeper analysis on the future of wireless, please contact me via information AT disruptive-analysis DOT com. I offer advisory services to governments, operators, vendors, enterprises & investors.