Perhaps. My general point was that it's unlikely to start with 17-18 year olds. If they were being sensible they would tap into the under-employed 21-23 postgraduate/post-college cohort, and invite those under 40 to apply.
Expectations are different today, obviously.
There used to be an expectation you'd serve your country in some capacity. Adolescence seems to be a lot 'longer' these days, too. Plus, all the modern complexities of ND, MH etc., which were not considered back then.
So there will be a lot of political battles to be had, and some clever policy-making will be needed to minimise the capacity of middle-class parents using their social capital to sharp-elbow their offspring out of national service.
Either way, there's not a lot we can do about this. If conscription arrives then there will be a level of compulsion but not necessarily going to 'the front line'. Factories will need to be built, land will need to be farmed, and so on.
For context, before retirement I worked in lots of public sector roles. I too would be useful in a voluntary capacity, and I would expect to be asked to serve in some way, e.g. classroom assistant, helping out in a care home, etc.