Not true for DIR-655. It was advertised (major focus point) as FREE UPGRADE to ratified final 802.11n be it software-based or hardware replacement.
Here is the official statement:
D-Link will continue to improve our Draft N series with firmware upgrades. In the event that the firmware upgrade is unavailable, D-Link promise our customers who have purchased our Draft N series (DIR-655, DIR-635, DIR-615) before 29th Feb 2008, a hardware replacement*. This is our promise to customers, who have incurred a higher cost in adopting the draft N technology.
Firmware for Draft N Series :
DIR-655 Xtreme N Gigabit Router
DIR-635 Draft 802.11n Wireless Router
DIR-615 Wireless N Router
* In the event that the model to replace is out of stock or unavailable, D-Link has the right to replace a different model with similar capability without prior notice or announcement.
This is the normal way of life for every part of electronics and does not depend on a new 11N standards.
If you think so, you'll never by new stuff because it is obsolete in a short time frame.
It is 2 and a half years now people told me not to buy a DIR-655 because there is no standard for 11N.
It is running fine up to now and will do so for the next years but nevertheless I will buy the "next generation" because I want to work with the newest devices.
I am very curious 
Most current devices will be updated and the others will work even without the final drivers. Why not ?
There are only minor, more cosmetic changes from the last draft to the final.
11N has a wide range of regulations and a wider range of what is possible, so there will be i.e. 300 Mbps 11N, 450 Mbps 11N and 600 Mbps 11N depending on the hardware you use.
All is full compatible with the final 11N.