I think that is kind of the only hope, that they lose morale. If Putin has his way he will continue to push. Frankly they haven't really engaged with the full force of their military yet, they have about 900k total troops with 2 mill reservists, and they have only deployed 150k-ish in the front and have only engaged maybe 1/5 of their arsenal. As Al stated, logistics is the concern for them now. If they can figure out how to support their troops in the field and can deploy even half of their current enlisted force with 1/2 of their arsenal this will take a different turn. The question comes, at what point is Putin willing to escalate to move long-distance means of attack, including potentially low-yield nuclear attacks. How crazy is he? Remains to be seen, it would appear.
Here is an interesting discussion around nukes in general and low-yield in particular.
Russia’s invasion of Ukraine shows the limits of nuclear deterrence
www.scientificamerican.com
Not sure if expressing shock and outrage is enough to deter their use.