I think dungeons would work better as they are on LFD but then have a second queuing option that requires you to have a full group we shall call this champion mode (similar to how flex queuing works). This 2nd mode is more difficult and has 2 extra dungeons that are far longer than the others (BRD style) All dungeons in this mode are harder and the end bosses reward epic items where as the rest of the items are the same as normal heroics but are higher item level.
All dungeon items can be upgraded one time to another 4 item levels in all dungeon modes. Requires VP, it works on epic dungeon items and non epic dungeon items. You can also buy some dungeon gear from the vendors but its expensive JP wise. This makes JP a good currency for dungeons. Make a dungeon tier set (drops in both modes one is a higher item level than the other both can be upgraded via JP/a unique quest line).
Have raid modes like so:
10/25 Normal and Heroic are available from raid release. If you choose to go heroic or wait to get gear first its up to you.
Flex 1st wing on raid release then 2nd wing opens 2 weeks after the 1st and then repeating like this until all wings are unlocked. This staggers the content for the masses.
LFR 1st wing opens 4 weeks after expansion release (so casual players have time to get things done prior raiding and ensures they run through dungeon content first) then every 2 weeks a new wing opens.
Have challenge modes in the game still have unique transmog sets AND weapons and mounts. With a leader board as is now.
Scenarios continue as they are with their H versions as well.
Add 2 dungeons per raid patch. The 2 dungeons have new items and either new dungeon sets OR you complete achievements/new quests to upgrade your current dungeon set to a new level or hell even acquire the previous tiers LFR/Flex raid set in these new dungeons. The dungeons you could only access via the challenge modes and champion mode dungeons can be added to the standard LFD queue and are re-tuned AND split into wings. This means casual players now get 6 new dungeons on the raid patch (if they never did a champion mode dungeon).
thats my vision for dungeons and raids at least.
Professions I feel should have more things to do, like dungeon drops as well as raid drops for item recipes to make things interesting. I would also have random world drops for items as well. Black smithing can also do armour repairs but instead of costing gold it would require metal bars. So if you are a black smith you can repair your own armour or armour of other people for bars (this makes it so its not over powered and more a flavour). Same thing for leather workers and leather gear and tailors and cloth gear.
I would also make enchants transmogable. You simply go to the transmog vendor and put in the enchant you wish to have as your "spell effect" on that weapon.