Engine update won't ever hit.
There is another game called "The Isle" who ran into the EXACT same issue, and they learned quicker that it's MUCH easier to simply RE-MAKE the game than to try to update the old one. (Google The Isle: EVRIMA / The Isle: Legacy for more info if you don't know what I'm referring to.)
LO Simply has to realize that taking a shortcut isn't the best move here. They're better off running 1.2 or whatever version they're currently running APB on while completely remaking the game in the new engine from scratch on the side.
YES, it's a long process. It's taken two whole years for The Isle to create EVRIMA, but the base game is done now, and official servers have been up and running for a year. If LO had simply done this, you'd already have APB 2.0 out, + a few updates, but LO made some stupid decisions and tried to save money and time with a shortcut that other companies discovered BEFORE them, wouldn't work.
So no, unless LO decides to finally learn from their mistakes and do what needs to be done, you won't see APB 2.0.