Yes they will. But you should never do that, not even think about it, future generations would be very mad at you.
Let me explain, nowadays this wildfowl face extinction, and it's not extinction by fisically vanishing but by genetic pollution because where they are native from the villagers have domestic chickens and sometimes wildfowl may breed with them which produces a birds that is neither a wildfowl neither a domestic breed its an mongrel dog from the bird world, that will further pollute the wild populations. So, this almost uncontrollable mistakes are bad enough, no need for people to do it voluntarily (which unfortunately still happens).
Some people nowdays believe they may be already extinct, but it's not widely accepted.
Consequences of this:
-It's is extremely difficult to find a pure bird in captivity (and catch wild ones may not be the solution because of the problem referred before, also it's illegal); In united states may be impossible, even at zoos (that don't sell animals for start) birds are not pure because of mistakes made(like this referred
www.backyardchickens.com/forum/viewtopic.php?pid=6625194#p6625194);
-A pure bird with DNA certificate retails for a LOT MORE that a regular chicken (sometimes hundreds of euros~=dollars) that's is why many people try to fool others, be careful; And are so exclusive that many sellers require you to be a WPA member to buy one from them.
So, don't think about doing that, and spread the message. Thanks
About what you said regard their looks, hens have to be like that because when they are brooding their eggs they must not to be seen by predators (camouflage) while cocks can escape, hens don't even have a comb. And in pure jungle fowl at the end of the breeding season cocks molt to a less showy plumage (no need to impress the girls anymore) called 'eclipse molt' so that they can go more unnoticed.