Swift outside of Apple is a long bet for now. It's just been open sourced and it competes with other languages in a crowded market.

As siscia said, you should probably pick a language that will teach you new things. Especially if you aren't hurting and in need of a marketable skill now. The investment will be worth more than just putting another similar language on your list. Why? Because you will learn to see things from a different angle and maybe tackle problems in more efficient ways.