Tnhats all nice and well, but the US doe snot apply all its defence budget onto Ukraine. Russia pretty mich does, currently, and boosted it. And it buys its stuff mostly form tiself, cheaply, getting far more for its budget, in quantity, than the US or Europe. Russian labour is cheap, so are Russian ressources and energy.
Again, all this theoretical arguments of If and When-Then does not affect the fact that the West lacks the will to go all in and produce and donate what is needed.
Which would be - by factors - more than what has been given in the past 21 months together.
And the US' ongoing support is questionable. If the courts do not stop Trump, I assume he will become president again, seen from current perspective. And top of his agenda is to take revenge and settle open bills, what he sees as open bills. Even a Biden or other democrat president will have problems with Senate and/or Congress to endlessly pass costly bills on Ukraine. There is not only the ME war, but also Taiwan. So, it is likely US support for Ukraine will not grow, but will wane. And the Europeans alone cannot compete with Russia'S wild determination to either destroy Ukraine or to win the war.
Not to mention that there also is no political unity in views and opinions. Poland has scaled down its support. Germany is naked. France holds back. Spain and other distant Western-Southern EU states have little enthusiasm for supporting the war. Some EU countries still heavily buy energy from Russia. Even the US still buys uran from Russia. France sends nuclear material to Russia for reprocessing. Austria, Hungary, Italy, Spain buy huge, decisive quantities of gas. Bulgaria is an uncertain candidate for NATO loyalty, since it loves Russia quite much.
I would predict that even if Russia directly attacks a NATO country, there still would not necessarily be unity over article 5.
Potentials and realised materialization of potentials are two totally different things. We could perform better. But its just that we do not really want that, for various egoistic motives. And in parts that is even understandable. Its not as if we do not have no problems, economically and financially, at home. We have- Huge problems.
Salushnji understands this and sees it as a big risk, thats why he publicly somewhat confronted Zelensky'S formal optimism in that essay for the Economist. He is very much aware that if the West does not do
much more, Ukraine hardly can keep its things together endlessly. Ukraine hangs on a Western drip, that simple.
If things run on like this year and support raises not by factors, then Ukraine will lose.
And now be honest to yourself - how likely is it that support will dramatically increase, by factors...? 
I see no signs for that.