In a game where accounts and be bought and sold, I think the critical question for this banter is "How do you define a veteran?" Case in point, my oldest character is from 2007. I played him for roughly 6 months and then abandoned him for close to 7 years. By the definition of character or even account creation date, I'm a 9 year veteran of EVE, but in terms of subscription, I've only been playing for 3. Account age does not seem to be enough to measure veteran status.
In a game where Alpha clones exist, using subscription time as a measuring stick excludes all those playing your game for free but perhaps spending significant amounts of real life cash for ISK or Skins or other in game items. Subscriptions then are also not a reliable measure of a persons veteran status in the game. The rewarding of loyal customers, then is perhaps more relevant.
But I think here you have similar challenges. If you cannot measure by age of account or length of subscription, do you measure by time played? I'm sure some very loyal, though perhaps more casual players would take issue with any measurement that evaluated the time in game. My characters are logged in almost 24x7 sometimes as I routinely check on them, on corp chat, and enjoy the convenience of them being at the ready even though most of the time they sit idle.
It is fairly easy to see why the act of rewarding player based on any kind of longevity would be a significant challenge to CCP. The road they have taken has been one with a variety of rewards. We get rewards annually on the anniversary of the game. We get rewards around the holidays. We get rewards at Fanfest. We got rewards when Alpha clones were released. And as mentioned in the blog, purchasers of the collector's edition have a code which was used for a number of rewards and could be in the future. The official CCP responses I've seen stated that future mystery code gifts would be given when there is something significant to give to those who have it though the latest response can be found here. CCP Falcon mentions that changes to the redemption and payment system this past November were involved in any decision about future gifts though that time has now passed.
First, I do think CCP should continue to provide value to the mystery code. The longer it languishes without any type of use, the more it feels like a feature in EVE desperately in need of iteration but long forgotten. CCP has come a long way to eliminating this perception from the game and it should not let the code sit idle too long and perpetuate this feeling.
Second, I think CCP does a good job providing us with in game items as rewards for playing the game. We have gotten various ship skins, pod skins, and of course the novelty gifts. It is difficult to amp up the rewards without venturing into game breaking territory so skins and other cosmetic gifts are likely the extent of what we will ever see with truly free in game rewards.
Where I think CCP can perhaps innovate, is to implement some of the ideas that have been thrown around regarding player recognition. It has been brought up before that CCP could implement monument in a system as a way to honor people who have left us. While not specifically rewarding to veteran players, the history of EVE and those of us who play has permanence and such a memorial would certainly cement that idea within the game. Additionally, lore events and other use of in game story also create ties between players and the game that have lasting effect. Many players recall that CCP even went so far as to threaten a player in game with a bounty for the return of an in game, lore related item. These game and player interactions are excellent ways to reward players in unique and interesting ways for their actions beyond what might be done as simply a reward for playing the game to the general population. Giving us, as players, more opportunities to be written into the permanent history of EVE in public ways would be a great use of some resources within CCP