The speed limit is the speed of light.

With that in mind the universe is infinite because the "edge", if there is such a thing, is moving away from us faster than that.

If you enjoy being anxious about things you can't prevent or even detect then how's this:

It's possible that our local presentation of the universe is just local, somewhere out there are other "big bangs" which occupy the same spacetime but at immense distances and their "edges" are approaching us at the speed of light.

We wouldn't even see them coming. We'd just be hit with an overwhelming amount of radiation before we know it.

(this is likely "not even wrong" in how wrong it is, but I do like a cheery thought)