In a lot of ways, the proposed Planning Study is hard to find consensus about because there's so much conjecture around it. But it's important to note that the most speculation revolves around areas that already have tons of potential to build new units "as of right." A commenter suggested that the parts of the Lefferts neighborhood experiencing a boom are already contextually rezoned. However, this is not correct, as the map of current zoning (above) shows.
The above includes areas of CB9, but everything from the south side of Clarkson down is CB17. Just below and to the east of Clarkson FlatBed is a lot of R7-1, though R6 allows for all manner of nutty stuff, as the planned 23 story tower down Nostrand past Church shows. It's zoned R6, so clearly you don't need R7-1 to go high - if that's your primary concern, which as Q readers will note, is not the only thing I take into consideration.