Actually, as we all can see, they are pumping out T-80BVMs at a steady rate.
Which already required some new parts and systems, and tooling, and all the stuff.
And finally - the staff
Sure they had tons of parts/systems stored, but if they will end up with serious digits of tanks in ranks, those will be there for the next 30 years.
This will obviously deplete the storage of spare parts and surely requires establishing a new production.
This war has proved one more thing that hardly anyone would imagine.
West is impotent, in general.
Lacks production cap, technology and ... money!
It is 19 months into a war.
And as I said, not a single new Euro made tank was rolled out of the production lines.
We talk Brits, Germans, French and Italians - all produced tanks in the 90s.
We talk Poles, Czechs, Croats - all produced tanks in 90s!!
Not a single Eurofighter, nor Rafale ...
Every single new piece delivered to European armies, are made in ... Korea.
It is an overall fall. Total and absolute deindustrialization.
That all combined means, that T-90M or T-80BVM is as good as it is now - both won't face a serious competitors on the battlefield.
And if will - a swarm od Lancets will take care of those.