I'm not an insider, but the MTO website refers to making HOV access permanent for vehicles with green vehicle plates. Seems that it's just a matter of procedure at this point.
The following vehicles have unrestricted access to HOV lanes, no matter how many passengers they are carrying :
•buses of all types
•licensed taxis and airport limousines (currently until June 30, 2016; ministry has proposed to extend until June 30, 2018)
•emergency vehicles
•electric vehicles with green licence plates (currently until June 30, 2016; ministry has proposed to make it permanent)