No, they won't do it forever. It's just a case of what I call "the puppies"!
I don't remember when Muffin stopped running like that. It will end, though. I wouldn't worry too much about them getting hurt. They are both old enough that they have quick reaction time and will probably "put their brakes on" soon enough. Kacee still does that and she's 6 months old. She'll go running through the house and sometimes jump up on the bed with the stairs by it and go rolling across the bed!
I just hope she doesn't roll off onto the floor, but they're more flexible than we give them credit for, too. I used to have a chihuahua that did that and I can still remember that we said it sounded like a herd of elephants running through the house!
We couldn't believe anything so little could make that much noise...