I'm going to find the Gameboard action regarding D&D 3.5 an interesting one to watch. My reason is that I know of one distributor that broke the release date for the initial Harry Potter TCG and found it difficult to obtain product as Wizards of the Coast, and in fact Hasbro blacklisted (refused to supply) the company for several months. In fact what little I know, even now they find certain lines difficult to obtain, having to source alternate supplies at a higher cost to themselves.
The difference is that this was a distributor outside the US as compared to a US based one. What will happen on US soil...
Unless Wizards of the Coast/Hasbro is prepared to protect their release dates and in turn protect their supply line from such actions, then they are risking such actions occurring again. Simply releasing the product earlier is no solution as mentioned, because many outlets will be indirectly discriminated against while they wait for their supply.
What it will need is for the parent company (Hasbro) to stand up and deal with the situation, to make an example of Gameboard Distribution so as to ensure other distributors will not step over the line. Even ones that are not directly linked.
If Gameboard is not an authorized distributor... then the source that supplied Gamesboard needs to be found and dealt with. By deal with, I do not mean struck from being allowed to distribute, but informed that they may no longer provide product source to Gameboard or be blackballed themselves. No distributor wants to risk losing their product lines, especially the ones that are ongoing. To lose access to not only Dungeons & Dragons, but the Harry Potter TCG and any other product line that is accessed from Hasbro and Hasbro divisions as a whole... no legal action, no lawsuit is required. Loss of supply for all product lines, even for a limited time period is going to put a rogue distributor back in line and will ensure that authorized distributors pay attention as to who they supply as regards sub-distribution.
If they ignore the situation, then they have no grounds to complain should it happen again... and when it happens again... they can't complain should stores simply drop their orders in the belief that they will be left in the lurch...or switch suppliers, affecting the authorized distribution network in a negative fashion.