Is it true that carriers are increasingly switching to calling over WiFi? I understand the new iPhones have this feature, with switchover happening automatically.

Did the popularity of Facetime, WhatsApp, etc. have anything to do with this? I have seen claims from carriers that WiFi calling "improves coverage".

At some stage, will anyone question what is the point of the cellular network? Especially in urban areas.

What is the difference between

a. a "smartphone" and

b. a portable, pocket-sized computer with rechargeable battery where the user chooses what to install and can remove any pre-installed software, where user gets a choice of 1. using pre-installed software and default settings or 2. using her own bootloader, kernel and userland, and where the user can easily open the case and tinker.

Does a computer need to have any association with the company selling internet access? Today's "phones" are manufactured for carriers (who are often ISP's, too), not for users. The carriers in turn sell these customized "phones" to users.