I know I've posted this in another thread and it's conceptual but Davie's G-LAM does answer many needs along with supplementing the 2 new AORs with some limited RAS capabilty. Large flight deck and hanger etc.Not arguing that something like that wouldn't be a nice to have capability...but there are lots of "nice to haves" on the list. Not sure that this one would make it into my top 10 though.
I don't see Canada getting into the opposed amphibious landing business any time soon, so what we're really looking at is littoral deployment capabilities into permissive environments. JSS can support deployment by Chinooks. AOPS and CSC's can support deployments by medium-lift helicopters. All of the above have small craft for over the beach deployments. If LAVs are needed we can deploy them by C-17 or JSS if required.
For emergency response along our own coasts one look at the map will tell you that wherever you place your handful of amphibious ships they are likely to be quite far away from where they are needed. Airborne deployments will certainly be your quicker response option so if I had to choose where to invest my limited dollars I'd pick additional aircraft over the amphibious capability. Aircraft also have the advantage of being able go places other than the shoreline.
Again, not discounting amphibs as an excellent capability to have, but in the absence of having the funds available to fully and properly develop the capability as @KevinB outlined above, then to my mind improving our air transport capability is the smarter way to go.