Why should we wait till 2018?
Let's start the Great CSS Battle right now. Me & my team have been using Fela as our major CSS-in-JS solution for about half a year. We used to work with srylecomponents before, but I just cannot get the idea of writing CSS & HTML in JS without JS syntax. For the same reason we switched from JSX to our own helper. Probably I will write the article one day which will show what we've lost in performance (spoiler: almost noting) and what we've gained in DX (spoiler: enormous boost). In a nut shell,I hope that 2018 will be the year when JS components will combine structure, presentation, behavior in one place, so developers will be able to replace three syntaxes with only one. That's what we did half a year ago...and our live won't the same again
Do you see this as being the final solution or do you think there will be more advancements in CSS-in-JS before it settles?
I don't believe in final solutions anymore. We live in a time of great changes and that's what I like in JS most. However, I do believe in reliable framework-agnostic patterns which born as enthusiastic experiments and then grow into enterprise standards. HTML Components is a great idea, but JS Components is even better. Developing all in one place using one syntax is our future. JS is a great way to achieve that. If you ask me about Fela, I would say that it is the best for my practical purpose: syntax, customization, performance, ecosystem and what is more important - the vision of the author and core contributors. They do care about performance (and a lot of other popular solutions actually don't). I put a bet on Fela, but even if it will fail (I really hope it won't)...well...it won't be a problem to switch because CSS as JS Object will remain as one of the main patterns for years. Remember this comment ;)