I don't think it's necessary to go car-free if it's pedestrian-first.
But streets like Laurier at University, Cumberland and Louis-Pasteur could definitely use some shared-space magic. Corridors like Laurier, Cumberland, Waller and Mackenzie-King, if made more accommodating to bikes and pedestrians, could help bring university life to downtown, Rideau and the market too.
As for the vacant lots, many of them should be developed. Perhaps the university should look at allowing some floors to be devoted to non-university uses (market housing, office space, active commercial frontage) in order to finance their construction; mixing the uses might ensure that the campus is populated during more hours of the day and that its infrastructure (like parking lots which are empty at night which could be used by residents) are getting better use.
Just as importantly, many of the brutalist buildings need to be retrofitted to be less aggressive towards the street and confusing for their users. Morisset library, for example, would greatly benefit from an entrance onto University instead of forcing everyone into the claustrophobia-inducing rat-maze that is the University Centre.