This is a user forum and NO one here knows (or could tell you if they knew) what Apple's plans are
What do you want to do - the Ken Burns effect provides a zoom and pan which you can set as you want - so you can set a slide for Ken Burns effect and by your settings have it still, have it zoom only, have it pan only or have it zoom and pan
If you want to zoom in on something select that slide, check the ken burns effect for it, set the beginning view you want by zooming the slider below it and panning then click on end and set the ending view you want the same way -- now when you show the slide show it will start with the view you set as the beginning view and transition to the view you set as the end view
LN