I would imagine that the course will be reasonably fast assuming what I know about organizing events in this city and what roads you get authorization to shut down.
Up and down the gats could slow things down.
Honestly I would thank Gatineau Park is “too hard” to make an IM successful. Each 42km loop is 680m (or so) of vertical). that is literally a 2800m vertical race. At best one loop and back to Ottawa on the various parkways, but I would think that with all the bridge closures and also dealing multiple layers of government (city of Ottawa, city of gatineau, NCC and multiple police forces), going across to the Quebec side is a pain (although the Ottawa Marathon does deal with all of that so who knows).
If I was organizing it, I would just close the normal Sunday bike day parkway routes, and you can easily have three loops of 60km WITH NO ADDITIONAL HEADACHE for the city compared to the same roads being closed EVERY SUNDAY. For the citizens of Ottawa nothing changes. The same roads are closed as every Sunday and on that weekend it is just an Ironman rather than random citizens cycling.
Further to that if it “just multiple parkway loops” (Western Parkway + Colonel By alone is 42 km round trip from Brittania to Carleton U as that was the Ottawa marathon course back in 1993…also my PB open marathon). Add in a loop on Queen E and you have 52km and on Col by all the way to Hogs back makes it 56km. So you just need to come up with 4 km more somewhere if you need to come up with 60km (maybe a loop thru carleton U). A course like that would be around 400m-500m of vertical for the entire race as you would need to climb Parliament hill 2x per loop and go to Hogs back 1x per loop. It’s not totally flat but fast enough that people will keep coming back because the course is not TOO HARD (compared to Tremblant or LP).
Lots of hotels downtown assuming most of the run is downtown on the paths (easy to do at 4x5.5k out and back) like in Nice or Zurich and jack up the atmosphere. They could make the run “harder” going down by locks behind parliament hill. Lots of possiblities without going up to Gatineau Park. If I was the organizer, I would not take on that headache because the upside of how nice it is there, is not worth the organizational headache and slow times people would have.
We all know that easier courses with atmosphere “sell” so this is what I would focus on.
Now if this is happening I truly hope they have a 70.3 on the same day to both keep numbers up and selfishly so I can race.