using hard drive space as a limitation in regards to the blocksize debate seems misguided, bandwidth and latency would become bottlenecks long before hard drive space would become an issue for most people. It is possible to fit more then two hundred copies of the blockchain on an 8TB hard drive. Hard drive space certainly should not and is not a limiting factor in regards to the blocksize debate, especially when compared to bandwidth and latency.
Yep, couldn't have said it better: bandwidth and internet availability as a whole are the issues. More to the point, hard disk technology is possibly set to undergo somewhat of a renaissance between now and the early 2020's, so storage tech performance limitations are unlikely to be the source of network problems related to blocksize increases.