I think there may be some mileage in this idea too, but I think that the new universe that was created inside a BH would have to be of a lower dimensional order than the universe that the 'host' BH was a part of i.e. if our four-dimensional universe is within a BH then that BH exists within a five-dimensional universe. Similarly, any universes that might exist within BHs in our four-dimensional universe would only be three-dimensional.

Part of the reasoning behind this is that there is infinite n-dimensional space within a finite sized n+1-dimensional space. For example, there is room for an infinite number of zero-dimensional geometric points along a one-dimensional line of finite length, just as there is room for an infinite length one-dimensional line within a finite two-dimensional area, and so on...