Unity is free, Unity Pro is $1500. Unity iPhone Basic is $400, and Unity iPhone Advanced is $1500. (Oh, and Unity3D is a different engine entirely. Seriously, it is. We’re talking about Unity here.) They just got over $5 million in funding (in addition to being self-funded and successful before now), do you really think they’re just going to take the money and run?
Unity has a free license, there are many features were are not available with this version. Unity Tech is not, by any means, abandoning the software. They’ve received a $5mil investment recently to continue their growth.
The free license isn’t a sign that the engine is dying, but a marketing strategy to attract new and potential developers who would hopefully find it worthwhile to buy the iphone or pro licenses.