Remember when the Twitter experts said the Russians only had a 3 week supply chain and then they would collapse?
They were right about Russia's logistical issues but any quick end to this war always hinged on Russia deciding that the cost was too high to continue.
The military expert folks always laugh at them when they bring out their cold war (or even WW2 era) tanks and guns but that shit is reliable and very easy to use. You load a shell, you fire. Any idiot can do it and they really don't care what they hit.
In the same sense even a half-working tank is better than no tank.
Right now Ukraine is waiting on German missile systems that need to be refitted because their targetting doesn't work with British/American missiles. These weapons were crucial at this stage but have been delayed until fall.
They are also waiting for Polish Leopard tanks stored in Switzerland but Switzerland won't transport them to Ukraine. The Germans promised a bunch of Swiss-made anti-air tanks but the Swiss aren't willing or able to supply the ammo so it's being sourced from Brazil which will take far longer. Poland is now entering a contract with South Korea to build tanks based on a Korean design in Poland. Thus they will no longer depend on Germany, France or the US/UK for tank production. However it will take time to ramp up production. The UK is the most reliable partner for Ukraine along with the US with their arms shipments but those stockpiles aren't endless either. There's also talk about 'sabotage' of shipments (weapons not working or parts missing) and some Ukrainian militia units selling their received equipment (such as Javelins) on the black market.
Ukraine is now fighting on a 500km (~300 mile) front. Biden is sending 4 HIMARS missile systems I believe, while capable those are not nearly enough to defend the front. Weapon shipments need to increase 5 times, maybe 10 times to keep the Russians at bay and most of all they need long range weapons. Those Howitzers they got from the US and Ceasars from France are a big help but again not enough.
As the war progresses and they run out of their own stockpiles the Ukrainian armed forces are starting to look a lot like the Wehrmacht did in WW2. Plenty of advanced high quality and high maintenance weapon systems with unique capabilities in low quantities but simply not enough regular artillery guns, machine guns and assault rifles.
Not only does Russia have a surplus of all their basic weapons they produce themselves (and tons of ammo) but they've also exported those designs to other countries (China/India etc.) so they can easily source additional ammo.
So while Russia might run out of cruise missiles and hypersonic weapons, they won't run out of AK-47 ammo or artillery shells anytime soon if ever.