The following argument is logically valid:
1. Potentialities exist. (Premise)
2. Potentialities are real insofar as there exist certain entities capable of actualizing them. (Premise)
3. Potentially, the universe could have failed to exist. (Premise)
4. Therefore, an entity with the power to actualize the universe exists. (From 1 - 3)
Now, an entity that has the power to actualize something as vast as the universe must be very powerful, to say the least. It must also be timeless, changeless and immaterial, given that this entity transcends the universe (the sum total of all physical space, time, matter and energy).
Seems like a promising argument to me. It's a kind modal cosmological argument that I admit I hadn't heard of until engaging in a Thomistic discussion forum.