Content Additions (Score 2, Interesting)

I have a series of questions but any one being answered will make this avid gamer happy. Has any thought been given to extremely difficult and rewarding five man content? Are there any plans for single player instances that involves severe amounts of skill as a player? Are there any plans for further character advancement beyond grinding for gear? Or are there plans to add questable pieces of set gear that compare accordingly to some end game content?