One of my peers who reluctantly entered management is very technically capable, but an expert of an older platform. He is planning to get back into the Software Engineering side of things, and asked for my opinion on the most marketable platform to be an expert of for the next few years.
I'm a Microsoft expert, so I offered up specialization in the .NET platform and Sharepoint, which can be very intellectually rewarding and pays well.
However, I wanted to offer some other visionary insight into emerging platforms. What other platforms would you consider, that meet the listed requirements?