In other ways, you can't have your cake and eat it too, Either the OLP vote collapses completely, and both NDP and PC gain seats across TO, or the Liberals hold the inner core and some outer ridings in TO and finish with more seats in TO than the pundits are currently projecting. You can't have OLP collapsing in Toronto Centre and holding in DVN. My prediction (subject to Kathleen Wynne's performance in the debate) is still that the Liberals will hold on to at least 7-9 seats in TO, and many of them will be the seats NDP are targeting - we'll see.
Yes, you can. Universal swing isn't a thing outside of theory. It assumes every place has similar voters swinging in the same way. See Lib Dems in 2015, where they mostly collapsed except in a few places with popular incumbents.
Also, DVN can have anti-Ford tactical voting for Liberals, which won't be a thing in Toronto Centre (where PC is totally out of running).