Most PowerPoint template designers think that what you put on the empty template page sets the look and feel of the presentation. Gradients, watermarks, logos, color bands. I have long been arguing that the template can just be a blank white page, what sets the look and feel is your approach to how your design the slides: what shapes, what colors.
The new iOS7 is a good example. Icons that looked great in iOS6 now look dated instantly in iOS7. The design philosophy has changed, without new logos, or repeated graphical elements on the page. It is the combined power of the new iOS7-ready icons that together create that new fresh layout.
So in PowerPoint, pick your colors, your fonts, your approach to shadows and gradients and you can use a simple blank page as your PowerPoint template.