Yep. Ukraine is also a populous country. It will be years before not having the theoretical manpower will be a problem, and if the K:D ratio passes 4:1 in Ukraine’s favour, Russia actually runs out first.
In the end it will probably come down to political will. Russia could dissolve into a mess of coups, the West could kind of just move on, the West could have internal problems that make it prohibitive to keep supplying Ukraine, or Ukraine itself could start re-evaluating exactly how willing it is to give up a bit of territory for the sake of peace.