"operable airplane hangar style doors"? -- I guess it
could work. But I don't see why it would necessarily have to be something as elaborate as huge movable doors. It wouldn't have to be like the roof of the Rogers Centre (or an airplane hangar door) that would need to be frequently opened and closed in 20 minutes or less. They could just take a few days each autumn to set up a barrier at the back of the seating area to enclose it for the winter, then in spring take it down to open up the view from the lawn area, if that type of system would be cheaper and simpler to build than permanent huge movable doors.
link
... The previous (and current) problem with Ontario Place was that we had to safari across an asphalt desert from the GO Exhibition Station and Exhibition Loop (and future Ontario Line's Exhibition Station) to get to and from it.
The additional entrance and pedestrian bridge over Lake Shore Blvd have been needed since it was built, and should shorten the walk a little. It's only about a ten minute walk and I don't find it to be an exhausting trek, about the same as getting from Union Station to Rogers Centre. Maybe during the CNE and Indy race weekend there could be shuttle buses from the TTC loop to the Ont Place entrance, if they don't already do that.
I've always thought that if they're going to rebuild the whole thing, it might be a better idea to instead build an entirely new venue closer to the GO/TTC station, either inside Exhibition Place or on the Liberty Village side just north of the rail line, but that's presumably not a practical suggestion since Live Nation already controls the Budweiser Stage site.
And this should sink the other (OverActive Media) entertainment venue proposal, if that's still being considered as viable by the city. I'm assuming Live Nation would have no trouble coming up with enough money to follow through with their plan, unlike the other proposal still clinging to a faint hope of finding investors and a significant equity partner more than two years after revealing their plan.