They do not have anywhere near a billion dollars. It would be idiotic to have this as a public spend - let the developer build a (smaller) park that ends up doing the same thing anyway.ORCA is DOA. City is pursuing the full park through a traditional public funding model. They have a ton of money from cash in lieu parkland payments from all the development over the last 15 years sitting in an account and waiting to be spent, and the rail deck park is a place to spend it.
You have developers wanting to deck the rail corridor from Bathurst to Yonge - let them do it.