Considering that tanks for me cost $58 each, and a month and a half ago I was having battles where both sides lost up to a total of 5000 tanks per battle, I'd really like to see ground warfare become even a little bit more realistic especially since this the setting is more modern. And it irritates me to no end that soldiers appear out of thin air, no mercenary company would EVER hire out to a nation that loses most of it's soldiers. Although as someone said I'll think of a way to suggest this in the suggestion forum, (after making sure it hasn't been suggested before).
As for navies, I won't be able to afford much if any of them for, i don't know, a year perhaps.