Any military action in the modern era is doomed without dominance of the skies, which the Ukraine has not.
Russia as a modern state can not be beaten in a conventional war without air power. A few stinger hand held rockets will replace an active well trained air force. The deeper the cuts into Russia will only serve to rally Russian public opinion for the war. Even now Europe has lost her ardor for the war and supporting Ukraine. The more Zelenskyy clamps down as a dictator—the less people feel comfortable supporting such a government. In the end —it will be the people of Ukraine and not Putin who will force him from power. But, the war goes on—now in Niger (where France and the US will be forced to invade), In the Arabian gulf, In Syria to support the Kurds, In the China Sea to support Taiwan’s Pro-liberation Party, and other lands. We will be eaten alive in distant places. Russia is—the least of our worries.
Yup, its why the Afghan's lost to the Soviets, right?