There's nothing I'd like more than to see another DNS-343 firmware update, but the reality is that new product lines were released, like the DNS-320 and DNS-325, and I'm sure there are more to come. I don't know if D-Link will continue to support the DNS-343 in the way of additional firmware updates, but they did do a good job for the few years that the product was out. Newer DNS models are benefiting from the hindsight and lessons learned from the DNS-343 and other legacy DNS models, resulting in continued improvements on the newer product lines.
As for the demise of the DSM-520, now we have the Boxee Box, a revolutionary product with rave reviews that's running circles around the competition.