Volunteer professional armies is probably going to be the best way until we get decent robots or all become some kind of nano particle/AI swarm. As such conscription is a tricky sell for me.
If you are going to have a draft though then with modern mechanised industry, and with a mixed military already, I don't see why it should not to both sexes.
I will note the split between combat roles and non combat roles.
As far as women in combat. There would be two potential downsides
1) General strength, endurance and such. Men statistically having considerably greater stature, more muscle mass, different bone structure possibly leading to different types of injuries (having to squirt babies out tending to favour different hip/leg styles)...
Ignoring the bone structure thing I am sure there are some women out there that can make the grade (and I will want identical ones here for combat roles). Statistically that is a far lower number though, and modern military concerns are largely all about the statistics.
For combat roles then, despite what others have been saying in this thread, muscle is important -- the weights of things people are carrying these days (the higher end body armour is not light
https://www.military.com/daily-news...mor-may-be-too-heavy-combat-report-finds.html , and gear wise they always want people to take more -- a fully loaded L85A3 is some 5KG and most countries don't differ too much here for combat rifles, ruck loads vary somewhat but some 30KG (60LBS or so) is average with it shooting up to 90 or 100LBS for other various roles, ideally which any unit member should be able to fulfil if theirs downed -- knock out you squad's automatic weapon carrier... and there is a reason they call it a force multiplier). It has diminishing returns after a point but stats still come back
Similarly 46.7 kg is the completed weight for a HE shell for the new M777 artillery (
http://www.military-today.com/artillery/m777.htm ), while it comes as pieces that adds up quickly enough and it is not like they are so many that you end up with a bunch of nice 5kg weights to build up a stack. Do you want to tell the people expecting supporting artillery fire that you got a little bit tired and had to reduce the rate?
Still in all work type things I am all about make the grade and you can play.
2) The "protect your women" thing bred into people for millennia at this point. Unit cohesion is very important and things which could upset that are tricky (discipline, morale, repetitive training beyond basic). Will such things lead to unnecessary risks taken or less aggression than might be needed? Would it be easier to take your already statistically small fraction of women out rather than have to beat such ingrained behaviours out of your people (especially if that takes time you could do on other training, or on deployment, or..., and if it has to be renewed as well... well then).
Other psychology could be a factor but it is not like they care about PTSD after the fact, and otherwise seem to have cracked the getting people to kill thing (though I still have my issues with the bayonet training thing that did the rounds a few months back -- some said it was harsh, I am not so sure), so I will ignore that for now.
There is also the possibility for pregnancy thing but I will assume everybody is professional and avoids such problems.
Non combat roles is also not without its concerns -- while a supply unit would ideally not have to have contact with the enemy... an army marches on its stomach and everybody knows that so cut supply lines where you can, possibly even as a priority at times. How many women are going to be able to drag 120KG out of a burning vehicle? Does this further reduce roles available? Mortar fire hits your supply depot and are you similarly going to be as able to drag people to medics, save stuff, drag things around so they don't get consumed?
One then asks are there some kind of extra role that women could fulfil that men might struggle to, or struggle to find as many to do, or just find them better spent elsewhere (front line combat and peacekeeping/quasi police actions are hard roles to switch between, despite having some similar skills between them -- clearing a hostile town and you see a curtain twitch but brush it off... standing in a "friendly" city and see a curtain twitch...). None appear immediately obvious here, at least not without downsides.