From a policy standpoint, it means less "lost productive years".
I get that historically grabbing dumb and easily inspired disposable males was the way because there was almost always disposable males in the old demographics for the last 10,000 years.
But modern urbanized society isn't like that. Children are precious, old retired people are disposable.
The West is being far to passive on Ukraine. There should be large amounts of European forces in Ukraine right now. I'm talking 100,000 minimum.
Russia has openly stated its goals to attack NATO if/when it gets Ukraine. Putin views Europe as a fat pig ripe for conquest, full of weak and cowardly leaders.
Total population mobilization has to be planned now. The Polish and Balkans, the most willing fighters in NATO in the next line of countries, should likely be actively mobilized for total conventional war.