Remember the Tu-160 was designed to counter the B-1A not the B-1B. The B-1A had similar numbers is speed and range to the Tu-160. Both those aircraft were meant to fly at high altitude to launch ALCM's. The B-1B was meant to fly at high speed and low level to launch ALCM's and SRAM's. Just because they look similar doesn't mean they have similar missions. With the Lancer's role today, you can't really even compare them anymore. The B-1B is a dirt mover, and the Tu-160 is a nuclear deterrent.
To maintain a strategic fleet of Tu-160's would cost to much money for most nations. China wants to be a economic super power and project power in the region of Asia. They have ICBM's to attack the U.S., they don't need Tu-160's to attack instead. They would be bettor off buying Tu-22M3's to protect their home waters and attack naval threats.