If you want them, as a company, to survive and continue to improve the software on the devices they run now and in the future, then you should welcome their taking steps to produce new products (earning them more money, which will help finance continued improvements to the OS).

If you want them to die due to lack of funding thanks to their only product being an increasingly uncompetitive device (just being realistic here - it was already not the hottest thing on the HW end when it was released), then sure, perhaps they shouldn't work on something new.

Spelling this out in a slightly different way: the intention, as I always understood it, was to run multiple devices from a single codeline. They don't have the resources, or desire, to repeat the Nokia mistake of branching entire OS development just because the hardware target changes.

tl;dr: The software that runs on your tablet, will probably also run on your phone (with some concessions for different form factors and the like).