Stifel analyst Jim Duffy says commentary from Ambarella (AMBA) last night around the timing of wearable camera product launches "strongly suggests" that there is a low probability of an additional GoPro (GPRO) camera based on an Ambarella platform being launched before year-end. This development, coupled with his impressions that the HERO+ LCD and HERO4 Session cameras, despite being well received, are not "necessarily driving the category to new levels," has made the analyst lower his estimates for GoPro. Duffy cut his Q4 earnings per share estimate for the action camera maker to 94c from $1.04, which is now in-line with the consensus. To reflect concerns about potentially decelerating trends for the action camera category, Duffy also cut his FY16 earnings estimate to $2.00 from $2.12, below the consensus estimate of $2.14. While GoPro's valuation is "intriguing" following the recent pullback in shares, there is insufficient upside potential to justify a Buy rating at this time, the analyst tells investors in a research note. The stock closed yesterday down $2.90 to $43.69. Ambarella, which supplies chips for GoPro's cameras, is trading down $7.41 to $82.20 in the pre-market after reporting Q2 results last night.