Honestly, I'm wondering if the Russo-Ukrainian War could devolve into something resembling the Iran-Iraq War. In the latter war, Iran had a 3:1 population advantage over Iraq (4:1 for Russia versus Ukraine, so more-or-less comparable) while also being heavily sanctioned while Iraq received a lot of Western military and economic support. Yet, in spite of this, even after years of warfare, Iran failed to deliver a knockout blow to Iraq or anything close to it (such as conquering Iraq's main port city of Basra) and thus eventually gave up fighting because it realized that several additional years or more of fighting was not going to make a crucial difference in regards to this. The same could also eventually be true in regards to Russia. Wasting hundreds of thousands of their men's lives in years' worth of needless offensives only to fail in all of them and thus to eventually give up the war/fight against Ukraine.