...how will brand new devices be updated to the latest OS version?

I bring this up, as Microsoft recently shutdown the servers for OTA updates for Symbian devices. Fortunately it is not too huge of an issue as Symbian devices are mature in the development community and it is possible to flash the latest version from a download-able image. That, or the various custom firmwares such as Delight.

The Jolla phone, on the other hand...I had to send mine back to Finland when the filesystem became too full and the phone became unusable. I tried using the recovery off my Linux desktop beforehand, but to no avail. There is no obvious way to flash a firmware image as it is known for Symbian and Android, I can't even find them online.