Yeah apart from those reasons... There is demand enough to make profit... But not as much profit as they want to make.
Your comment about EK is relevant, but will they be allowed into those markets? MXP-JFK kicked up a hell of a fuss. If EK35/36 were to continue on to JFK (after a second flight is introduced) I could see it working, although with slow growth, just as happened with NCL-DXB, which is slowly maturing into something many thought was never possible.
Just so I'm not seeming too NCL centric other routes I could see happening are DXB-MAN-LAX, possibly DXB-MAN-DFW/HOU and DXB-GLA-ORD. I don't think EK would be wanting to start out by going up against the big US legacies on routes to New York from MAN/GLA. LGW could be an option for transatlantic but slots could be difficult.
Emirates and their focus on new markets outside of Dubai will definitely be something to watch. Even though they still have a way to go from DXB.
EDIT: Didn't see your edit, do EK definitely not serve F from BHX... They have the new lounge and everything, same as GLA. I don't think it's fair to compare EY and QR to EK in terms of when/where/how they offer First class. QR is phasing first class out and EY doesn't have many more planes with first either. Emirates is the opposite, granted making them the oddball.