Re: Yes, they look beautiful
There's a reason that the speeds havent increased much from what they are now - it's called the Transition Zone, the area between subsonic and supersonic (0,8-1,0 Mach, so about 960km/h and up) is highly unstable and really bad for your cruising efficiency. By staying out of this area you save a bunch of fuel. Going into the Supersonic regime unfortunately causes lots of problems with heat, even just going slightly above mach 1.0, means your unlikely to be able to use Alumnium for your Skins anymore (at least not leading edge). Not to mention the problems with sonic boom, and similar issues.
Supersonic solutions have been looked at in the time since Concorde - most famously Boeing did the study of the Sonic Crusier. But theyre investigations found that economically, the Airlines werent interested because passengers were not willing to pay the premium to save a couple of hours of flight.
On the topic of Composites, it will be the next generation of aircraft that benefit from the weight savings of using Composite structures. Aerospace certification authorities are extremely conservative. Because there was no long term data on Composite structures under flight loads (i.e. for the entire flight life of an aircraft), Designers had to use huge safety factors on the Composites meaning they weighed the same as the old metallic structures. Now that the data is there, the next Generation of aircraft will be able to use reduced design factors and so weight saving will start. You actually already see that to a degree on the A350, as Airbus was able to use the A400M as its Composite test bed. Maintenance of Composites has also been a problem which is another reason for building them extra strong and heavy, but now that Solutions are getting real world experience the additinal safety factors for this will be reduced.
Finally, the reason all aircraft look pretty much the same is that they are actually pretty much the optimum design for Subsonic flight. Delta's and flying wings might be more efficient at supersonic, but for subsonic its hard to achieve any real saving comapred to whats already in the air. So sorry, but dont expect any major design changes until someone works out how to make a supersonic aircraft thats as efficient as a subsonic aircraft and does something about the sonic boom problem...