While I agree with the plan, the rest really won't work because of these reasons:
1. QBL is at capacity.
2. 75-footers cannot go on Myrtle. This would require sending all of the 68s from the B to the N/Q/W for 160s. This would create longer dwell times along the line because 75-footers have increased capacity with the same amount of doors.
3. Most people won't take the M because it runs as a QBL local.
If people really wanted a good connection from the Rockaways to Midtown and lower Manhattan, I would send a line from 96th street down to Prospect Av, running express on Broadway. After Prospect, it would run express to Church and then run down a new line under Flatbush Avenue to Rockaway Beach Blvd, where then it will run over that to 119th street. From there it will curve to Beach 116th St station. This however, would require relocating buildings and rebuilding the entrance/exit of Beach 116th St station.
As for the Flatbush section, the line would be 3 tracks with a peak direction express service. Express stops would be located at Nostrand (transfer to the 2 and 5), Kings Highway, , and Utica Avenue. Local stops would be included at Clarendon Rd, Avenue J, and Avenue N. After passing Avenue V, the line would emerge and run alongside Flatbush Av, as well as merge into two tracks. A summer-only stop might be added at Floyd Bennet Field. From there, the line would travel on a new bridge to Jacob Riis Park, where another stop would be located. After that, the line would run along Rockaway Beach Blvd to 116th with stops at 142nd, 133rd, and 124th.