Unreal Engine 4 is not the only one that will be switching to subscription model as Crytek has announced that its CryEngine will be available in a new "engine-as-a-service" program which will offer subscribers the full CryEngine toolset for US $9.90 per month.
Unlike Epic's subscription model which offers the Unreal Engine 4 for a significantly higher monthly fee as well as a 5 percent of gross revenue from the final product, Crytek will offer its full CryEngine toolset for US $9.90 per month and free of any further royalties.
Crytek has also announced that it will continue to offer its free CryEngine SDK but the free version will not get all the new features revealed at GDC 2014, including planned update for AMD Mantle API and Linux.
Crytek did not go into specific details regarding the "engine-as-a-service" program and it is most likely that it comes as a direct response to Epic's Unreal Engine 4 announcement.
In any case, it will definitely be an interesting battle between engine makers for developer affections.
Source:
Crytek.com.