Will you make content to please hardcore PvE community?

Regarding challenge modes specifically, there're a few bits of information that the developers have commented over the past days on live chats and social media, which I believe might be interesting for you:

-Challenge modes have no lockout (so you can try them as many times as you want in a single day).
-These are harder than level 90 heroics, you can't outgear them (gear will be normalized inside), and certain things, such as set bonuses will not work. Trinkets do, though. At least for now.
-The developers hope that the time required to get "gold" in challenge dungeons is similar to achieving Gladiator in PVP. Meaning, someone sporting a whole set of challenge gear should be akin to seeing someone in a Gladiator mount.

The theory is that challenge modes will fill this niché, but if past experience is anything to go by it will either be too easy or will be subjected to nerfs.

Still, can always hope.

The developers have commented this several times. They do expect that most players will be able to achieve Bronze as long as they play properly. Silver is a step up in that regard, but you might still be able to stop and consider your next move before further progressing on the instance.

And finally, the design philosophy for challenge dungeons is so that the developers don't intend to lower the bar to get silver/gold.

19/09/2012 15:47Posted by Taishici

Problem with challenge mode is it is restricted to 5 man. 25man guilds will have to pick the best and make groups. If this was in raiding part of wow then yes players would be happy.

Well, on raiding, as it's been mentioned on the thread, you'll be awarded a Feat of Strength for defeating the final bosses of each raid instance without the debuff. And the Protectors of the Endless encounter in Terrace of Endless Spring has even better loot if you defeat Protector Kaolan last (which makes the encounter harder, in a similar way as it happened with the Iron Council in Ulduar depending on your kill order).