Carbon wheels are lighter, stiffer and generally stronger, especially if you’re after aero wheelsets.
Tubs (tubular tyres) are generally lighter and typically more comfortable to ride on, even with the 140psi plus pressures you need to run them at. Big downsides are they’re difficult to repair, can be very expensive and because they are usually glued on, you do need to be a bit more careful at the extremes of riding;- fast downhills, fast corners etc etc.
Tis very easy to blow £2K or more on some high end hoops.
Re disc brakes. Ha Ha, no chance that’ll happen on high end road bikes.
They don’t need need them and the focus in recent years has been towards aero. The Scott Plasma 3 is one of the slipperiest Time Trial bikes at the mo though manufacturers are chucking more effort into making conventional road bikes more aero.
Take a look at the Cervelo S5 to see where things are headed.
Oh and on a vaguely connected note, Rockshox did some lightweight sus forks for road bikes back in the 90s for the pro peleton.
Didn’t catch on for a whole host of reasons, weight and flex being two biggies.