Currently, I own two Macs. My main computer is a 27-inch iMac; my backup computer is a 12-inch MacBook. Perhaps by 2018, I'll own just one Mac: a MacBook Pro with a 10TB flash drive.
That's not as ridiculous as it sounds. Announcements from Micron and Intel about new 3D NAND flash advancements hint that upcoming Macs can be equipped with greater-than-10TB solid-state drives. Currently, the MacBook Pro, iMac and Mac Pro top out at 1TB PCIe-based flash storage upgrade option.
The new 3D NAND technology stacks flash cells vertically in 32 layers to achieve 256GB multilevel cell (MLC) and 384GB triple-level cell (TLC) die that fit within a standard package. These capacities can enable gum stick-sized SSDs. For a standard 2.5-inch drive that means up to 10TB of space.
Even with my iMac, I keep my music, movies (including dozens of ripped-but-legally-purchased DVDs) on a 6GB external drive. Imagine if all my iMac's internal and external store could fit into a 15-inch MacBook Pro. Such a system would become my main Mac for both work and play. I could use it anywhere to do anything from updating Apple World Today to watching movies.
One flaw in my plan: I'm crazy about the 5K display on my iMac. I won't be buying any high-end Mac laptop until I can connect it to a 5K, 27-inch Apple display.
Of course, I don't know that such systems would be affordable for most of us. However, Intel and Micron claim their 3D NAND technology will mean lower cost per megabyte (as well as less power consumption).