The US has been relying on its 1980s Abrams and 1990s Javelin designs way too long...
Sure, this new Russian tank has a lot of capabilities...but so did the T-90, T-80, and T-72...all still part of the active Russian forces. New platforms...new training...new specialized maintenance equipment...multiple spare parts systems...multiple types of ammo.
Upgrading the M1 series instead of developing entirely new platforms has its advantages.
BTW, the Russians still have T-64s, T-62s, and T-55s in their reserve forces.