@innsertnamehere has already outlined that the current MTO work has not included rail within the footprint, and shy of removing lanes, that there isn't the room remaining.
I think the point was that room should have been found when widening/corridor planning was being undertaken.
Clearly, that opportunity has been missed.
I will let
@Sauga89 speak for himself.........but there are a few reasons to consider reconnection to the north.
1) Network Redundancy for freight and passenger service.
2) Ontario Northland would be more economical if it serviced Barrie.
3) The connection allows for current and future growth for Orillia and provides an Orillia to Barrie connection.
4) It allows for service marketed to those Cottage/Resort/Park bound. (clearly this requires substantial 'last mile' services not yet in place, be that car rental/carshare, cycle rental/share, or some form of transit.)
The last one is somewhat more fanciful in the near term. But the first three have at least the hint of a business case to them, subject to how expensive any reconnection work is.........
But important to note here, that Sauga89 wasn't suggesting building the connection anytime soon, merely protecting for it.