Stop asking people for what can or can't be done. Ask them what to do and how to do.

Nobody knows how much you can improve, since it hasnt been around for thaf long anyway.

If you did it with sheer hard work and dedication, I believe you should be able to totally correct macro dystrophies, as well as have at least some effect on feautres as well.

tl;dr give it your best and you will see results. That much i can assure.

Your tongue strength will determine your advancement on things like this 

Like most things in life, what's possible depends on your starting point and your capacity to progress. Unfortunately it seems like the worse off you are, the harder it is to improve. If your palate is too narrow, or recessed, or asymmetrical to get your tongue into the correct position, it can't do the work of expanding your intermolar width or moving the maxilla up and forward. Appliances won't do the work for you but they can be helpful to get you moving in the right direction. If your anatomy already allows you to get your tongue into the correct position, then it is just a matter of habitualizing that form, building the strength of your tongue and masseters, and you should see improvements over the course of several months. However, if you can't get your tongue into position it becomes a protracted process of incremental changes, which can be catalyzed with an expander or other devices, but still take years to achieve satisfying results. Most of us are somewhere in between, where we can get our tongue into a compromise position that isn't ideal but still helps. In such cases an appliance might or might not be useful. The good news is that your relative youth should make progress easier.

Thank you