"Now personally I think once the inventory system is fully implemented these two classes will disappear and will instead just be equipment options for Traitor and Jump Assault.
Suppose my question is will the ground assault classes be kept as they currently are, as a completely separate class, or will they be merged into their parent class (Traitor and Jump Assault respectively) once all the shiny bits are here?"

Now I am just thinking out loud here, and just putting forward another possible path that the devs could take regarding the future of these two classes. I see two possible paths that could be taken. Like everyone else said you could see a merger with the JA becoming more diverse with the player having access to a lot of customization, with equipment modifying the JA stats.

I think your post is on the right track and is a good start for how the devs could merge the two classes, if this is indeed the path they are going to take.

The other path I see (and it is complete subjective and speculative), is the devs could take GA and MoN class and use them as starting point/ foundation for how to incorporate and balance the Leader, and Elite classes that EC intends to incorporate into the game. The classes we are playing now in the Alpha could be an attempt as to how they can make these classes different between the factions as well as how to balance these classes with the primary classes. Elite and Leader classes need to be better than the primaries but at the same time they shouldn't be able to clean the field.

I don't know about everyone else, but the way these classes are currently set up and how they play in the current game, the MoN and GA really strike me in both appearance and feel as being "Elite-like", and both have the potential to be used starting points to make Vanguard Veterans /Sargs and Chaos Chosen/ Champions.

Anyways that is my two cents. Thanks to the OP for bringing up this question, I too was wondering about this myself.

Cheers.

Isn't one of the chaos advantages that the traitor assault can cap points? If they merged the class would they still keep this advantage over the SM for example? That's the only concern I have, 4 or 5 classes makes no odds to me.

As it was stated before. Ground Assault classes are not actually classes. They are loadouts for testing purposes. SM GA is the same class as SM JA. Wile Traitor Assault is the same class as Traitor. That is why Traitor Assault can capture points and SM GA can not.
But it is all so counter intuitive that all the forums are filled with cries about imbalance. What we are trying to get in this thread is some statement from the Devs whether it is still as intended, or they came up with some other class variants. The thing that sparkled this discussion is a screenshot from steam in the OP's message, where Ground Assault is portrayed as a separate class.

I wonder what GW's position on the issue is. The original plan and the info on this website is to put the "tanky" components in the Chaos Traitor and in the Loyalist Assault classes and end up with four basic classes for these two armies. I'm pretty sure GW gave its approval to that plan because that information is totally public. It is also what many of us are expecting (hoping) the developers to implement.
I just don't see why we - or GW for that matter - should accept the Loyalists having two separate Assault classes and Chaos having two separate Traitor classes, that would just be a poor performance on the part of the developers.