Back to Unity, I think the only thing that would save the engine + share price would be a Microsoft acquisition. That would actually be a really good move for them.

Nah, Microsoft would make some decent changes on the frontend for usability and improve code formatting like they did with XNA in the first few years, and then forget it exists like a ton of their other API (Microsoft Works, anyone? Silverlight ring a bell? Spark?).

Unfortunately Microsoft has had a horrible track record with design services and sustained scalability.