So if the City saw fit to run a DMU service along the (mostly) existing rail RoW between Kanata North and Greenboro, it might look something like this:
Note that I have chosen to extend the line into the airport. This provides a direct link between the airport and the high-tech sector. Travelers from the airport to downtown would either take the # 97 bus or transfer twice between trains. It would also be possible for the Trillium Line to go to the airport and the Riverside South people to be connected directly to Kanata North. That way, everyone coming from the airport will need to change trains to get anywhere.
The biggest issue I see is the conflict with VIA across the Rideau River. VIA says that their single track is already causing them scheduling problems. However, the problem is that their single track extends for a long way; meaning that a train between the Fallowfield and Ottawa stations blocks any train from entering from the other direction along that entire length. That might not be the case for a DMU slipping in to use the short length of the bridge. I hesitate a bit to suggest that idea since it would mean reconfiguring the signals along both sets of tracks – and we know how competent the City is with changing rail signals.
Remember, too, that just because there might be a rail RoW that might be available, starting up a DMU service would not be free. First of all, the tracks would need to be replaced with continuously welded rail on a reconditioned bed, including proper passing sidings. And, then there is the design of a new signaling system for the line; so it might never actually work right.