As long as Ukrainians can continue to destroy Russian armor and artillery as quickly as it is coming in, Vlad will eventually run out.
We are seeing a race to determine who still has sufficient effective assets when the other side runs out. But a single tank formation will not be enough to take the entire country. Vlad will need enough armor and artillery remaining to take and hold each city he wants.
Vlad's advisors might impress upon him the need to retain enough armor and artillery to hold on to what he seized before. Let's not forget that the Ukrainians now have abandoned armor at their disposal.