The new Ghast update adds support for the frozen Nether fan theory. You will soon be able to save Dried Ghast by rehydrating them with water, and then tame them with snowballs. This hints that ...

There's a new block called the Dried Ghast that can be rehydrated to form a new mob variant called a Ghastling (baby ghast, essentially), which in turn can become the new Happy Ghast mob variant.