AFAIK based on various bits and pieces of information it looks like Jolla actually strongly prefers just working on the software (Sailfish OS) and licensing it to others, rather than selling their own hardware (that they have to design, manufacture and support). The current Jolla phone being a sort of a proof of concept and the Tablet being something similar + free money from Intel for using an Intel CPU in it.

I would myself rather prefer Jolla making their own devices as I'm afraid third part devices might miss some of the unique Jolla features, such as ToH and might give more incentives to Jolla open source stuff so that they have something to license (IIRC this has even been stated a few times by Jolla people).

The last point is IMHO quite short-sighted, as you can still license your trademarks and artworks/themes/etc. while keeping the software itself open source. You can also charge for support, enhancements, certifications, etc. And it is not some crazy unproven idea, there are companies that are doing this rather successfully.