Middleware could be the most interesting choice but is high risk
Middleware tends to be needed as a platform matures and architectures start to coalesce. At that point the inter-communication between different applications on different machines becomes necessary so that users continue to have the same experience regardless of their gateway to the data.
For example, synchronizing contacts between your Anroid phone and your Google account and then verifying them on an iPhone makes use of some sophisticated contact management middleware (the Google Contacts Data API).
From the sound of it, you are being given the opportunity to work on software that facilitates arbitrary inter-platform communication at some level. If that software has the potential to be licensed and sold to application developers then you could be in the money. However, that is a either a high value sale (think expensive developer plugin) or an ongoing service (think web service with paid for login). It may be that an open source equivalent pops up and kills the purchase market, but opens the service market which may be bad news for your employer.
To sum it up, if you go down the middleware route then you're shifting your focus from specifically developing an Android application to working on something that works on many platforms. That may not appeal to you so much.