As much as I would love to see the back on QBL, it would be very unwise to restore service on QBL.
First of all, QBL sucks on the weekends, and by adding an another line, you're only going to make things worse, espically when CBTC work starts. Also, there's not high demand for direct service to Brooklyn from the QBL. Second of all, the actually runs better in its current service pattern than it's previous one. Your only going to screw over the entire line by extending it further.