Many of the above answers are correct I think.
I would add these two cents:
We have become accustomed to mobile technology being adopted at very rapid speed, and that is not sustainable long-term, nor even desirable. Don't expect new complex standards to become adopted as fast as, for example, smartphones evolved to all have fantastic mobile cameras.
Think back to desktop computers and laptops - standards like these take time and stability before reaching a critical mass.
As others have mentioned, one thing slowing down adoption is the fact that existing technology is for the most part sufficient, and there is no critical need for the new standards.
I think USB-C, or same near variant of it (maybe USB 3.3 or something like that), will reach critical mass within 2 or 3 years. In 5 years, it will be easier to buy a USB-C cable in a corner convenience store than a microUSB cable.
Until then, USB-A to USB-C and USB-C to USB-A dongles will be our life, like it or not. If you buy a non-USB-C laptop today, you will need more and more dongles over time as accessories begin to come with USB-C standard, but when you do finally upgrade to a USB-C laptop it will be great. If you buy a USB-C laptop today, you will need lots of dongles today, but they will become less and less useful as accessories begin to come with USB-C standard, until one day you will realize you don't need the dongles anymore, but by then you'll probably want a new laptop anyway. So, go hike a mountain, enjoy nature, and don't worry so much about cable standards, because you're going to live a dongle life either way.