What needs to happen now is for the second beta to throw-up as many bugs and glitches as possible so they can get fixed before launch, and the beta is also an opportunity to get some more pre-launch feedback.
It's taking between now and November to set up the beta-test servers, thus the beta should probably last a reasonable amount of time since they'll want to get the most use out of it as they can. I'd estimate the beta will end shortly before or after the start of December.
From there, the team have to fix any remaining bugs and glitches, and look at the feedback for necessary changes and tweaks, and get all that done (in the case of the feedback changes, that would involve keeping the community updated and in the loop) - which would take upwards of another month at the very least.
So it's incredibly unlikely the rework will arrive in 2018. The best-case scenario right now would be the start of 2019 (Jan/Feb), but it's almost done in any case and shouldn't be delayed too much longer.
Swift Punch1said: LOL, with Jagex they say November this year, it really means 7-11 months later.
To be fair, unless they receive overwhelming feedback of "this is all terrible, you did it all wrong" from the final beta, I'm fairly certain it will come out before April of next year.
And a reminder that the reason it's taking so long was because a few months ago they polled either doing a shorter rework, having it come out in batches but being available sooner, or doing a full rework and having it take a few extra months.
Now we're here with player choice being "lets wait a few months for the full rework" and people wondering where it is.