What Russia can't do is afford any of this. Forget the sanctions, their economy is small, and not willing to under go the hardships of the communist era. So they've been forced to use older gear, and their newer gear has been crushed in combat.
And don't forget that most militaries have old gear. B-52, B-1, B-2, etc are old old airframes. M1 is an old tank design (though it has been upgraded heavily). Bradleys are an old ICV design, again upgraded heavily. But the US still uses M113 from the 70s in some units, the Blackhawk and Apache are from the 80s, and we have ships in the USN that are almost old enough to qualify as senior citizens.