What if the IND Second System was Built?

This video is the result of me going down a rabbit hole of the IND Second System. So, what will happen if the IND Second System gets built?

Sources
https://www.vanshnookenraggen.com/_in...
https://www.vanshnookenraggen.com/_in...
https://www.vanshnookenraggen.com/_in...
https://www.nycsubway.org/wiki/IND_Se...
https://www.nycsubway.org/wiki/Histor...
http://www.columbia.edu/~brennan/aban...
https://www.nytimes.com/packages/pdf/...
https://www.nytimes.com/2018/01/03/ma...

Pictures
https://en.wikipedia.org/wiki/Propose...

https://en.wikipedia.org/wiki/Great_D...

https://en.wikipedia.org/wiki/72nd_St...

https://en.wikipedia.org/wiki/Signali...

https://en.wikipedia.org/wiki/Propose...

https://en.wikipedia.org/wiki/Astoria...

https://www.pexels.com/photo/bird-s-e...

https://en.wikipedia.org/wiki/Staten_...

https://en.wikipedia.org/wiki/Greenpo...

https://en.wikipedia.org/wiki/Bowery_...

https://en.wikipedia.org/wiki/BMT_Jam...

https://en.wikipedia.org/wiki/Houston...

https://en.wikipedia.org/wiki/Frankli...

https://en.wikipedia.org/wiki/Robert_...

https://en.wikipedia.org/wiki/William...

https://en.wikipedia.org/wiki/New_Yor...

https://www.pexels.com/video/traffic-...