@Skoll3 WebKit exists, it's just that nobody does marketing about it except Apple via Safari even in it's embedded devices space (it's either a chromium fork or webkit anyway, chromium being a pain to maintain since you'll probably be forced to do your own fork).

And I'd say it's still possible to write another web engine, specially for some devices / use-cases where all the desktop bullshit doesn't matters, but you need to have a team, great leadership and time.
Team and leadership that you're going to need for a chromium fork btw, if it's too few devs they're going to burn out because there is 0 fun in chasing after Google's whims and you're going to have some deal breakers.