There’s a darn good reason why commercial airplanes rarely go over 500 or so miles per hour. It has to do with the tradeoff of how much you carry and how efficient it is to move that load. As you go faster, the amount of power needed to overcome air resistance goes up exponentially. Also, your design is restricted by where you have to land. The faster you go the faster your landing speed because to go fast your wings must give less lift at slow speeds. Therefore, you end up landing faster and using lots and lots of runway.
Swing wings are a compromise, but they have proven ridiculous as they are too heavy, leaving you with a fast plane that carries not much or a slow plane that isn’t as efficient as a purpose-built design at that speed.
“As you go faster, the amount of power needed to overcome air resistance goes up exponentially.”
...which is why supersonic planes will need to fly at about 50,000 feet (or whatever) altitude.
Three years ago I took the Hawaiian Airways Boston to Honolulu and then the return Honolulu to Boston. It was at the time the longest nonstop inter US flight(11 1/2 hours going west).
On the return flight the jet stream was so strong that our flight broke the record for the fastest land to air speed record inter US for a commercial airliner. The jet stream tailwind was really cooking that day. We got back in just over 9 hours.