In my experience there are times when using the same element in all the different layouts becomes unwieldy, and it becomes much easier to have two versions of it which are hidden and shown with media queries, then altered for the specific layout. So at that point it's really not much different than actually having different templates on the server side.
About the conclusion (one performer/many tricks), I agree in that now that responsive design is our new toy, designers can go a bit crazy with vastly different layouts for different viewports. This may distill over time to an approach that aims for one layout that more or less works for all viewports, with only small differences between them.
Comments
In my experience there are times when using the same element in all the different layouts becomes unwieldy, and it becomes much easier to have two versions of it which are hidden and shown with media queries, then altered for the specific layout. So at that point it's really not much different than actually having different templates on the server side.
About the conclusion (one performer/many tricks), I agree in that now that responsive design is our new toy, designers can go a bit crazy with vastly different layouts for different viewports. This may distill over time to an approach that aims for one layout that more or less works for all viewports, with only small differences between them.