In a recent interview Blizzard once again confirmed to still be considering sub-races like brown orcs, Dark Irons, and perhaps even more extreme ones like Taunka and Earthen and stuff. One question they themselves were asking is how people would like to see these sub-races implemented, if they were added into the game? That seems worth asking the community about.
One option would be that bam; they are put in and immediately available to everyone. You'd be able to roll one as your very first character, just at the character creation screen, and start playing from the main species' starting zone.
A second option would be to give them their own intro story. This can give the sub-race a little custom lore, matching the intro quests for the other races. Even if they keep this short, it would certainly add more work-load to Blizzard. Still, some may prefer it, and I'm sure there are those would like the lore insights, to make sense of it.
Thirdly while you may not like the option for new players to just role these sub-races, you may want the option without hassle, when you're an experienced level 100. I'm sure Blizzard could make having a level 100 character a prequisite for unlocking sub-races, the same way Death Knights came with a level 55 character requirement. This would make sub-races something cool for alts.
A final fourth option would be that in order to get access to a sub-race, you have to unlock them in some was. Achievements, questlines, dungeons, rep. Maybe you only get access to Taunka after recruiting them for the Horde in the Dragonblight quests? Leper Gnomes could require the Gnomeregan achievement. How about completing the Twilight Highlands quests to get Dragonmaw and Wildhammer? Complete Blackrock Depths and Spire for your Dark Iron Dwarves and Black-skinned orcs? I am sure there are lore-related areas suitable for each sub-race. Hinterlands for Forest Trolls, etc.
But this thread isn't about what I would like most. It's about your opinion! So, let's hear it. If Blizzard gives us sub-races, how would you prefer them implemented? Like one of the options, or have your own alternative idea? Make it known!