>

You got a point, but Russia is not Germany. The latter was industrialised and a world leader in metallurgy and chemistry, etc.
Interesting. Though of course, not ruling something out, and actually doing something are two very different things. Still, the fact that they're putting the option on the table is telling. >

It's posturing. A calculated move to make the enemy work overtime to figure out their contingencies as well as their diplomatic response. 
Obviously, from an ethical point of view, Ukraine ought to be free to launch missile strikes on Russian soil.  I think it's something that the west is saving for the possibility of a near-russian victory. >

Britian already said they are cool if they target Russian territory with the weapons they give ukraine.  
It was only the USA that apparently made that stipulation. >

USA priority was degrading the Russians military to the point they can't do something like this again for like 20 years.
That goal has been largely met so now focus is forcing them to surrender by military defeat >

I think that a generation is defined to be 27 years. It will take several generations before Russia has the population surplus and financial surplus for another war. >

You could inform yourself with the state of Germany in 1918, and the resulting colossal war paybacks, to understand that what you say does not make sense. In 1939, the same country started a war again and bulldozed most of Europe.