Considering that zoom involves loss of resolution as soon as the image is cropped, as an option, the zoom could switch between 0.5x, 1x and 3x rather than the smooth zoom.
I think what you are asking is already possible with our upcoming 1.5 update.
When you disable digital zoom in Manual Mode, you will only have the option to switch between the actual lenses, without any zoom changes.
As mentioned in the Kickstarter Update, the new version will be out this week.