CLRVs were always designed with couplers. Multiple unit operation was tried with a set in Boston, but never applied here. That's when the skirts were placed on the front of the cars. If you look at photos from when the CLRVs first went into service, couplers on the front are clearly visible.
"On March 17, 1980, three Canadian LRVs from Toronto, Canada, (4027, 4029, and 4031) began revenue service on the Green Line. The cars, built by Hawker-Siddeley of Canada, were being tested to evaluate their performance as a possible final replacement of the PCC car. Although the tests of the CLRV were deemed a success, the MBTA instead opted to contract with Kinki-Sharyo of Osaka, Japan, in 1983 for 100 new "Type 7s".
[Photo]: On loan from the Toronto Transit Commision, car 4031 leads a two-car train of CLRVs at Auditorium inbound. The CLRVs were operating Riverside to Park Street in this view taken on May 11, 1980. The time that the CLRVs were in Boston is believed to be the only time that they ran in multiple-unit while in revenue service."
On further reflection, I think that routes on ROWs like Spadina and St. Clair (fingers crossed) are more likely to get the new low-floor streetcars, while pairs of old cars would be used on Queen and King, where the lack of platforms at the stops make low floors less useful.