Looks like there was a small mix-up in YIMBY. The site with the four skyscrapers is 115 River Road and is being developed by local hero Fred Daibes. Best part of all, this has already been approved!
615 River Road is a larger site down the street owned by a nonlocal developer.
http://615riverroadpartners.com/
A similar amount of units of units are planned at 615 River (~1800; 115 River is 1919). 615 River is the site the city is threatening to take via Eminent Domain.
I made a new thread about the real 615 River road development
here.