This is fairly significant for pet collectors, considering one pet is tied to the Pandaria Challenge Modes. Guilds who have yet to unlock the Thundering Serpent Hatchling by completing Challenge Conquerors: Gold - Guild Edition will be out of luck once the current Challenge Modes are closed. Granted there are some guilds who have this pet available and would welcome pet collectors to join just to obtain the pet, but it's still disheartening to hear that future guilds won't have access to the hatchling.
There are a few things Blizzard could do to keep this pet accessible to the majority, though none of it is likely.
- Stick the Thundering Serpent Hatchling as a reward for the next set of Challenge Mode achievementsConsidering how Blizzard is ok with the Challenge Mode transmog sets and achievements becoming unobtainable in the future, I highly doubt they would make an exception for the pet. The argument that the pet will still be around and not completely inaccessible (although you have to find a guild, get into it, and then reach certain reputation with said guild first) will probably also keep them from providing another source for this pet.
- Provide another source for the Thundering Serpent Hatchling (quest, drop, vendor, etc.)
- Create another guild related achievement (that's not expansion-exclusive) with the Thundering Serpent Hatchling as a reward
While I understand the reasoning behind it, it's still a downer. No one likes to have things taken away from them, and guilds that haven't unlocked this pet may feel that way. The hatchling itself may not be removed, but the option and the chance to acquire it for a guild will be gone.
There's still some time before the Challenge Modes are closed (I believe the official cut off is patch 6.0), so it's still possible to complete everything. Some players and guilds will end up scrambling to get it done, even going to such lengths as to pay others to unlock the achievements and pet for them. It's a fairly common practice apparently, and with the Challenge Modes going away "soon", the demand and prices will only go up. I find it distasteful, but I can't say that I'm against it 100%. I don't blame those offering this service or those taking it. If anything, I feel that Blizzard's choice to lock the Challenge Modes is in the wrong here, as it will cause desperation and panic.
A smaller concern is that guilds will start charging collectors to join and acquire the pet. This doesn't worry as much though, as WarcraftPets has an open guild (US server Madoran, horde - Magical Menagerie) for everyone to join (for the pet or otherwise).
The pet isn't being removed or going away, and so long as players can find the right guild to join it will be available to collect. Yet there's still a sense of loss for future players/guilds who won't have the satisfaction of unlocking the Thundering Serpent Hatchling for themselves. Times change and we have to move forward, I get that. In Azeroth, Blizzard dictates the when and why, and all we can do is try to adapt and cope. It's still a sad day when we "lose" a pet due to those changes.