The 15K tanks argument I have not heard since February last year. The absolute inferiority of older Russian tanks to modern guided anti-Tank weapons was so widely seen and demonstrated early last year, that no one is seriously disputing this.
Even Russian state TV is focusing a lot on the ramped up production of their newer tanks, APCs and so on.
Russian milbloggers meanwhile have over the past year widely condemned the lacking state of Russian hardware, the reported condition of which did not meet reality.
From what I read on the Telegram channel of Strelkov, the supplied western main battle tanks are a) far better in reconnaissance concerning enemy tanks and b) are designed to work in a interconnected way with the other supplied western armored vehicles.
That being said, I think that helping Ukraine to victory is the right thing to do. Tanks alone surely won’t do it, a mix of many different provisions will.
However, the political risk remains especially for Europe: what if Russia loses and turns into some kind of failed state? No one could want to have this kind of situation with a state of this size and power in Europe.
The open question in Russia has for a long time been: what, or who, will be after Putin? I thought it might be Medvedev, but his comments over the last year have been far more disconcerting than those of Putin himself. Likewise, the war is propelling other leaders to the political front line, Prigozhin and Kadyrov, and putting substantial military power in their hands, which they might use if a power vacuum were to arise after the inevitable death of Mr. Putin.
So as stated before, the aims are Ukraine winning by Russia conceding defeat, rather than being defeated.