It has crossed my mind this might have been a brilliant marketing ploy, if there was one (or a perfect flop, time will tell), after seeing the success of the fire sale. It will be a little hard for HP to turn on their head a few months from now (assuming the webOS catches on) and offer a better (hardware-wise) tablet, while forgetting about the customers that bought the first wave.
On the other hand, these customers will not be able to complain too much, given the huge discount they received. Apple has fooled it's customers repeatedly with new and "improved" versions of their phone and tablet and the discount was symbolic in their case (of course, one has to take into account the fact that their customers are extremely loyal and would not agree for one second they got cheated by their gods).
One final alternative for webOs would be to actually become just an OS, distributed to various hardware makers, like Android is. In this case, their best bet would be to expand support for cross-platform applications, i.e. to enable iOS and Android apps to run on their webOS environment. Imagine the freedom to choose not only the hardware, but also the best of all app worlds. If such an OS existed, I would jump in without looking back.