The Orca's are getting on to 20 years old, it would be good to start planning the replacements. Those ship designers Seaspan is worried about can be given the task of designing the replacement. It is interesting the base design for the Orcas is a Australian vessel, also doing training and also designed for Mine counter measures.
My take on the replacement
Primary role - training, replacement is slightly bigger to allow roughly the same accommodations, but on a more stable hull. This would allow them to sail further and not to be as weather restricted.
Secondary role - Harbour and harbour approached security duties. Hard points for a RWS forward and two MG weapon stations on either beam.
Secondary role - Ability to easily deploy a RHIB, support a small dive team or a small/medium sized ROV for route clearance duties. Side scan also needed.
Larger fleet - With the demise of the Kingstons we will need more of these vessels. A couple for the great lakes and some for the East Coast.