Apple has really shaken things up with their Metal API for graphics. Basically, Apple has redrawn the graphics landscape. They may be the first company to make very high performance graphics standard across a line of laptops. The Adobe demo with continuous zoom on Illustrator is impressive as well as the 24 frames per sec in After Effects.
Graphics API Cross Roads
People writing apps with superb graphics handling will have to make some choices. Cross-platform tool kits like Unity, SFML, SDL, Unreal, Qt and others will provide adequate visual representation. However, the software solutions by the name of Metal, DirectX, or Vulkan offer new considerations. How do you choose?
Uniform Apple Approach
The easiest route is to say you only do Apple. They have a reputation for the smoothest API with the least latency. Metal seems like a solid winner for Apple. If you plan to standardize on Apple and target Apple environments, Metal would be the way to go.
Next Gen Microsoft UI and Games
If you focus only on Microsoft, then direct use of DirectX technologies will be the most solid route. DirectX 12 is expected to shake things up in the Microsoft graphics world. People and groups with big budgets and an abundance of time will be able to fork to both. Several solid technologies under the DirectX banner on Windows.
Cross Platform Baseline
Everyone else, the closest you can get to parity with Metal or DirectX will be Vulkan. Many of the established and works in progress on cross-platform visual API may need to start again. Vulkan does mean that higher level abstraction layers may have to be revisited. This is a near certainty. In the short-term, that may negate the efficacy of tools like Cairo, Allegro, SFML, SDL, Unreal and so on or it may make them easier to implement and enhance. Their value could improve greatly as a result of Vulkan. Qt may be upgraded to apply Vulkan in a way that makes it more effective.
OpenGL will still work for several years. Yet, turbulence in API may eventually show the prudence of abstraction platforms such as SDL, SFML, Allegro, Cairo and others. In the meantime, unless you are focused on a particular platform, Vulkan will be the best choice for long-term solutions and abstractions that sit atop it. Vulkan, if done well, will be the default, pragmatic choice for solid, cross-platform graphics. The present downside to Vulkan is that it will necessarily lag behind the other solutions since it is designed by committee. It will be worth the wait since it promises to be a solid implementation supported everywhere.