Selenium 3 is finally out, so what does the future hold now? The next major release is going to be Selenium 4, which will align Selenium with the W3C WebDriver spec (https://w3c.github.io/webdriver/). After this has happened, currently there doesn't really seem to be much of a plan for future development. There will undoubtedly be enhancements to the W3C WebDriver in the future, which Selenium will need to align with, but W3C spec changes are not things that happen overnight. I think it's safe to say that the Selenium API will stabilize and the number of changes will reduce drastically.
So, if Selenium doesn't look like it's going to change all that much, what does the future hold? Well unless you have had your head buried in the sand, you will undoubtedly have heard lots of excitement around machine learning and artificial intelligence...