I am not sure if there are plans to allow a licensed full branding change but there are some branding you have access too already…
You can change the logo that is on the log in screen… you can add your own logo to tickets… you can not change the logo at top left when logged in.
To change logo at log in screen C:\Program Files (x86)\SambaPOS4\Images\logo.png
Look here for adding images to your tickets.