Does anyone know if GOG will be coming out with Xcom?

No. GOG doesn't mention future deals unless they are a sure thing so there is no way for us to know when or if GOG will get them.
You can get the whole collection DRM-free from GamersGate and Steam anyway (DOSBox games on Steam don't use the Steam service at all).

If you are looking for X-Com UFO Defense and X-Com Terror from the Deep, got check Steam. It is an digital distribution store (whatever it is called) similiar to GoG.

You can get the games pretty cheap and they are compatible with newer systems and PCs. I definitly recommend it.

I only really dabbled in X-com when I got it off an abandoware site many years ago. I remember the interface being quite irritating.

Do you think I'd get used to the interface with time? I always think that I might as well just stick with Jagged Alliance 2, which is very intuitive,

Hard to say. The interface really is quite terrible and seriously off-putting even for me who played the first two games to completion many years ago. It does get better when you get used to it, but the fiddly and needless micromanagement is still there. At this point, I'd recommend waiting for Xenonauts or the Firaxis remake instead; one of them is bound to turn out good.

My bet is on X@COM.

The interface of Xcom is actually pretty good, I like it and find it easy to navigate. Although that could only be me.