I was also thinking about the same thing. I think there are similar concerns while developing for both the platforms and if there is one person who is working on both there will be much better reuse of concepts and functionality. From maintenance point of view also it might be better if one person can do both.
I am not sure if big companies will prefer to have hybrid developers but smaller companies will definitely appreciate the savings and speed-up such hybrid developers could bring.
Pretty good point, actually - distinction between the small and large companies.
To date though, I only met two people who are proficient in both, and do it day to day.
I have been moving in the same direction. Trying to get proficient with both the platforms. I have got background in both Java and C++ so that makes it slightly easier.
At this moment, I am trying to explore if there is some kind of "economies of scale" in learning both the platforms.
If you're an employer, is this a desirable trait, or would you want just one stellar person per each platform?
For my company, mobile apps aren't expected for our service but we want to create them for a better user experience. So we would likely be fine settling for a mid-tier person who can do both over top-tier people who are specialized.