“RCA, OU and YI banned anything to do with Avi Weiss”
No, Rabbi Weiss was a member in good standing of the RCA until the day before he retired, The Hebrew Institute of Riverdale is an OU member shul.
As others have pointed out, YI is dying in most places, in part because it got too much into right wing politics and lost its identity. The two YIs in Riverdale are going strong though.