Economy will keep this conflict from freezing. The Russia's economy is spiralling downwards, possibly unrecoverably. That country will go bankrupt. Inflation is eating people's savings in terms of how many grams of bread you can buy with your salary. That will make people discontent.

And also, the Russian soldier is in it almost purely for the money. That means, the money paid to the soldiers must rise at least at the same pace as inflation. Which, in one hand, means that the government needs to pay more and more, and in the other hand that there will be more inflation because companies have to compete with the soldiers' salaries in order to get any workforce at all. Eventually the only way the Russia can pay those exponentially increasing salaries for its soldiers will be by printing money.

And when you print money, you end up with hyperinflation. And when the Russia gets that far, it's over with the war. Any Russian will understand at that point that retaining control over territories in Ukraine is less important than having an economy. USA can slow down the collapse of the Russia's economy, but it cannot prevent it. If EU joins in with USA, then yes, the Russia's economy can survive. But USA will be the only western country siding with the Russia, so the Russia is a dead man walking. Being the biggest economy in the world, the EU has a lot of say in this.

I wouldn't call it a frozen conflict if it has an end that is known to arrive.