Both viewpoints are valid to a degree.  Within local/national economies, a rapidly aging population is very difficult to support, especially given expensive advancement in emergency medical care. 

One way to mitigate this problem is to increase age of eligibility for social security/retirement benefits as average lifespan and quality of health in ages 60-80 improves.  Caveat:  will it continue to improve or will problems in our diet move us in the opposite direction?

On the other hand, I think the globe's continuing rate of population growth seems unsustainable, especially when the bulk of said growth is from low-skilled, poorly educated areas. 

One way to absorb this problem is to actually continue to encourage immigration to areas with aging populations and low density (the Americas) while continuing to open up trade barriers so that economies eventually function as one across larger territories.  This involves serious political considerations as well as significant generational setbacks in areas affected by globalization. 

However, one taking the long view (100 years or more) will I think see that the path toward further globalization and integration is both a way to generate more total wealth and insulate from market crashes.  In the long view of history, as the world's technology has caught up with its size, there has been a generally unbroken march toward expanded economic integration.  What makes us think this might be stopped now?  Or that it even should?

Also, increased integration allows the world to more easily pressure countries or companies who are environmental liabilities.  We aren't really seeing this happen to a great degree outside of Western Europe, but I suspect the loss power incurred by the USA post-Iraq will make it a reality soon.  And China will find itself constrained as well, eventually.