It seems that last part of a watch that remains mechanical is the strap. And that’s where brands like Mont Blanc are focusing their efforts.
The new strap, part of the Montblanc Timewalker Urban Speed collection, is a little metal screen that can receive notifications and messages. From A Blog To Watch:
The e-Strap features a high-end leather strap that has a carbon fiber texture to it that Montblanc calls “Extreme Montblanc Leather” and is produced by them in Florence, Italy. At the bottom, sitting under your wrist is an electronic module made from DLC (diamond like carbon) coated steel or in gray steel. Apparently, there are a few color and size options.