Interesting panel discussion, between Orange, Qualcomm & Acer.
Orange & Acer are both of the belief that people are happy to have multiple mobile devices, albeit maybe not carrying them all, all of the time. Qualcomm is more emphatic about its own research showing consumers are happy to carry 2 devices, some of them 3, but very few 4.
Depends a little on the definition of "carry", however - pocket vs. bag, for example.
The Acer speaker made a good point about needing to tie them all together better "which device has the photo of my friend?". But he was very emphatic that there is no need for a "Swiss-Army" all-in-one.
Interestingly, the moderator (from the US) seemed surprised about this, citing US research which shows people tend to prefer a single phone/device. I suspect this once again reflects the impact of cheap handsets & non-contractual prepay SIMs that are used in the rest of the world - there is a much lower entry barrier to getting a second phone in Europe.