Christian, based on our previous conversations I understand some of your frustrations, and I think you make some good points here, but I'd like to clarify a couple things.
Selenium is a trademark owned by the SFC on behalf of the project which has an official codebase. It will always be factually accurate that the code in that project's repository will be "official" as far as "Selenium" is concerned.
The monorepo has been fundamental to the success of the project. It allows us to (mostly) have consistency between the languages (every binding implemented x in version x.y, etc), and has encouraged us to work together to solve similar problems. It hasn't been perfect, but there is a lot of advantage to being able to do things like having a single issue on Github and tagging each language that needs to do something to address that problem.
"Selenium" should be a collection of language specific low level libraries that implement the W3C specification, paired with a server that can act as an intermediary node between the binding and the driver. It's a good thing that it doesn't have significant opinions. I think this is one of the reason that many of us are sad that PageFactory & ExpectedConditions and the like are included in the code base because they represent opinions about how the low level code can be used, and, as it turns out, their design isn't what most people would consider a best practice at this point, but now we're stuck with it and having to deal with people using it.
I'm very partial to the model that Jari pioneered with Ruby. Jari used Watir, but he only implemented the low-level code in one place (Selenium), and then leveraged that code to create a separate WebDriver implementation of Watir. That separation of concerns has made many things much easier to deal with in both code bases. Additionally, it has allowed projects like Capybara and older versions of page-object.gem to build their own implementations with significantly different opinions than Watir. Selenium should be considered exclusively "browser automation," and unbiased toward the various ways it can be used.
One possibility for WebdriverIO is not to "merge" projects, but to follow this Ruby model. Now that there is good(?) synchronization code in base Node, and now that WebDriverJS is using it, is there a reason (there might be I don't know your code structure or JS enough to actually know this answer) that WebdriverIO can't use WebDriverJS for the low level driver calls, and maintain the higher level features and helpers and opinions in WebDriverIO code base? Is there something in the WebDriverJS code that is itself still opinionated in a way that makes it difficult to build additional tools on top of it?
Doesn't WebdriverIO still require you to use the java standalone-server? Wouldn't leveraging WebDriverJS code allow you to both remove that requirement for running tests locally and also make it so that you don't have to implement the updated W3C specification in WebDriverIO code directly?
My dog in this fight is that I would like to figure out how the Selenium organization (and community) can be more supportive in general of open source projects that use it (Watir, Capybara, WebdriverIO, Selenide, SeLion, etc). Maybe this is as simple as a page on the new website (whenever it gets released) detailing the options and perhaps advantages and disadvantages or target audiences, etc. Maybe someone has a better idea for what might help. I'm just looking for ways to support the work of people (like you) who have put a lot of time creating code that makes it easier for people to use Selenium (specifically for testing).