So it wasn't German very long, only 50 years.
As for Montreal, it will be interesting to see how the city evolves. I notice more English in my neighbourhood than when I moved in (8 years ago). But, there is also more French in the old anglo neighbourhoods of the west.
One factor is that a lot of "allophones" are perfectly fluent in both English and French. When you add in the francophone tendency to switch to English when dealing with anyone who shows even a whiff of not being a native francophone, a lot of francophone majority neighbourhoods may see English conversation.
(I'm perfectly fluent and speak French in public. But for the life of me I can't francophone friends to speak French. I think they all want to practice their English. Also, the Quebecois that care about Anglicization probably don't move to urban montreal)