According to Prof. Peter Forrest 12D spheres are very stable. M-theory suggests that (although our universe seems to have 3 real metric and one imaginary time dimension certain aspects of physics can be explained much simply if we assume our universe has about 10 or 11 dimensions. Benji's TOE assumes that our universe may be sitting on the skin on the 12D apple or peach, and that the weaker physical forces such as gravity are actually strong forces from adjoining universes which have been weakened by the greater distance the forces have traveled through hyperspace.
Lee Smolin suggests that black holes act as sexual organs where universes can connect with other universes and exchange information which influences the development of new universes that are formed. It is quite likely that similar evolutionary forces which resulted in gender separation on Earth, would be at play.
Similarly universes might come in different niche forms such as predators and prey. Also staged development ageing might also be expected.
The laws of thermodynamics, suggest that closed systems tend to increase in entropy (I.e. grow old and die). We may take heart in that according to quantum physics the macro level laws such as the laws of thermodynamics are approximations. General theories of closed systems suggest that things that are not fed from external sources will be imperfect and may eventually die. Another possibility is that while entropy at increases at one depth of resolution it may increase in at other depths. Whether death might be theoretically avoided nay later be discussed further, but the general reasons why death occurs on Earth are likely to also be present in the hyperspacial environment of our universe.
Cosmologists suggest that our universe is currently right on the balance between being to expand forever and so big it cannot sustain its own weight. Also it also appears to be highly efficient at evolving creatures like ourselves given its short age. Whether our existence is crucial or incidental to our host or super-system universe might not be easily determined but we might guess that just as we find most parts of our bodies have useful purposes that we likely perform some useful function of the universe, and it would be expected that the development of important organs would be fast-tracked.
If we make the assumption that lighter universes that don't pass on the ability to die wind up filling the hyperspace environment with genetically inferior stock which can be easily preyed upon then it is not surprising that our universe should be heavy enough not to necessarily have an indefinite potential life span. Likewise our universe needs to have a long but not indefinite life or if extra weight has some survival factor such as supporting higher intelligence or physical strength then we might expect evolution towards the borderline balance we see in our universe.