Mr. Saunders prescription is typical of a Canadian liberal's approach when faced with an influx of asylum seekers; just say yes faster. Unfortunately, this has been tried twice before and both times simply resulted in encouraging ever greater inflows and large backlogs.
Canada's interest in securing the existing border accord was to deal with a persistent problem of lax visa screening by the US State Department and a porous US border being exploited by numerous groups. To do away with it would simply encourage more of an influx.
Those persons who are currently crossing the border have all had an opportunity to apply for asylum in the USA; a system that is as generous as the Canadian.  While I realize the Canadian liberal elite is relishing it's ability to feel superior and demonize President Trump, the reality is the rule of law still applies in the USA and the President has only limited powers to influence the asylum determinations system.