Last week, something strange happened: First
Epic Games announced that you can now develop for their Unreal Engine for 19$/month (+5% of your revenue), making their AAA engine very, very cheap, especially in comparison to what they charged previously.
Then, one day later,
Crytek countered with a similar offer: CryEngine for just 9.90$/month.
I think this is a reaction to their now 'new' competitor, Unity, (who
just announced version 5), which for some time now is free for the basic edition. Maybe even Unity will now try to get cheaper, who knows?

What we see here might be a begin of the phenomenon known from various app stores: The race to the bottom, where the app developers try to undercut each other, and prices for the apps drop, so far that even 90% of the developers can't live anymore from their apps, and only developers of very popular apps survive. It's conceivable that this won't work for 3D engines: Those are incredible complicated beasts, and need a lot of time and resources to be developed and kept up-to-date. Making them available for peanuts can only be sustainable when you have many, many users.
I hope this move just didn't start the death of some nice 3D engines. It would be a pity for those developers to go bankrupt or similar.
Disclaimer: I'm the developer of the commercial 3D engine '
CopperCube', with which you can create games and 3D apps without programming, and I might have a slightly skewed view to this.