Personally I love the idea, and I think they should continue to develop items and content to offer as an added benefit to whoever would like to pay for it.
What I'd like to see purchasable:
* Level 90 Characters - $100 dollars per character
* Exp Elixirs (Triple xp) - $10 dollars per stack of 20 (one hour elixir that persists through death)
* Garrison Upgrades - $5 per tier upgrade per building (allows you to instantly upgrade one of the buildings in your garrison to the next tier. They revealed there would be 3 tiers per building, and the ability to put many buildings in your garrison)
* Mount Flight Training - $10 per character (after you do the initial quest to unlock flying in 6.1, so you dont have to do the quest chain over again)
* Mounts - $25 (usual price)
* Pets - $10 (usual price)
* Transmog Items - $15-$20 each depending on the type of item. Full sets of sweet gear could be sold for more (in the $30-$50 range)
This is just the beginning of the things they could do and offer as an added benefit in-game for real dollar value. I would love to see more options purchasable via an in game cash shop. Of course there would still be things to get out in the world free of charge, but these would all be just extras, rather than mandatory.
Do you agree with an in-game Cash Shop??