The onus of who actually automates the browser is moving from Selenium (the open source project) to the browser vendors. This will help with reliability and is also exactly what you're asking for:
I would be very interested in tracking the details you're hinting at to know when this is done and stable to use reliably. Do you have specific examples/issues related to what your tests today require that is unreliable / not currently possible using WebDriver with Safari and/or headless Chrome?
https://www.w3.org/TR/webdriver/