NATO thinks Russia can fight for another couple years.
This might seem demoralizing, until you notice that Russia is operating at full capacity for arms production, and can't expand significantly more, due to financial, labor and industrial constraints.

i.e. Russia has likely peaked, and will tread water until their losses exceed their capacity to replace them or their economy either melts down or can't keep up with war costs.
Meanwhile, Europe & Ukraine keeps expanding their arms production.