The Street Ratchada is coming to the Ratchada/Huay Kwang area. If you have lived in the area for a while then you'd know that it's opening up in the old Robinsons building.
According to their website, they plan on opening around mid October, 2015. Check out their site, looks like another cool, new, hip mall coming to Bangkok.
Website: http://thestreetratchada.com (it shows the days countdown until opening, but wait a few seconds and will redirect you to their main page)