Nick is worried because he knows the demographic trends are against him.
He sells exclusivity, but sees that the democratizing power of the iPhone crosses socioeconomic and national boundaries as easily as clouds in the blue sky overhead. No high net-worth individual is embarrassed to be seen using the same iPhone as a high-schooler with braces, or Chinese middle class worker (in fact, quite the opposite.). Such behavior flies in the face of the exclusivity that Swatch Group sells and this combined with the fact that, generally, there is only one wrist available, per human, for his products to use (and if that is already populated by a beloved Wrist Pod-like device, has to be troubling...)
His super premium brands need not worry, unless there is a wholesale move by premium users to trade the exclusivity of jewelry-level chic for the novelty of iPhone-chic exclusivity, and then staying there because of the utility (as with an iPhone UI, or for exercise or Apple TV or gaming control, etc.). It's his upper-market brands, and the value brand (swatch), all serving as aspirational brands that feed the hoped-for conveyor to his upper level brands that are equally at risk here.
Regardless of brand, or price point, for the most part, the Swatch Group product portfolio, only covers the "purse" portion of Alfred Sloan's* famous "For every purse and purpose" dictum, as, be it a Swatch or Breguet, the "purpose" part of Swatch's portfolio is tied to fashionable time telling devices that do not much more than that.
So his key worry (now that his father and Schwartzkopf are dead, truly the only guys I ever saw wearing a watch on both wrists) is that for the vast majority of customers, like the proverbial 99 and 44/100 %, there is only one wrist per human being, which can be seen as the nominal useful location for a watch, and now he has to battle for this real-estate against wrist-pod-like devices.
Given that a large number of his customers have the disposable income to be early adopters, and that if the Wrist Pod is truly cool and useful, like apple products are wont to be, SMH-Swatch Group's business model will take a hit across segments. (I think most dads and moms would rather see their kids faces on their wrist than some elegant Zifferblatt.)
As a long-time purchaser of his father's, and now Nick's, products, I think I am a reasonable proxy for the kind of customer he seeks (in the not ultra-affluent segments), and as such, he has to worry not only about losing me, but attracting the future new mes that might buy the upper-mid market models after having also purchased from the lower volume brands in his stable.
I see his recent purchase of Harry Winston as a move with two objectives, to try and bring some of the glamor associated with this brand to the Swatch Group, in order to move its horological portfolio further upscale - as a hedge against the encroachment of Wrist Pod like devices on his portfolio's volume segments, and possibly to build-up that business as a competitor to Swarovski and to shore-up turnover and profit lost to the coming tidal wave of Wrist Pods...
* Longtime Chairman of GM, then the undisputed largest automotive and industrial enterprise in the world, which after not recognizing the threat, or effectively responding to the challenge, of being "disrupted" by import brands faded from a position of profit and power (or aspirational desire.). As with size comes the benefit of confidence, yet the risk of isolation, group-think and Hubris...