Epic and Crytek have released their respective engines "Unreal" and "Cryengine" as free downloads for anyone and everyone to download and make games with them.
Only limitation is that if you want to use the game you will make commercially,you will have to make a contract with them,paying them 20% and 25% of your game's income respectively.

These engines have more options and features unlocked than e.g. the Creation Kit,and there is a lot more documentation of how-to's and knowledgbase about them.

Will Bethesda ever make an engine to distribute it that way ?

Very doubtful, seeing they use a lot of middlewares (Havok and so on) that they are not allowed to release.