The cost and difficulty of altering the concrete retaining dockwalls, and the concern over the impact of the promontories might have on inner harbour shipping seem to be the two big issues. Still, I don't see why it has to lead to a reduction in parkland facing the harbour.
Proposal Three, "Harbour Park".
Parkland can still be made within the existing retaining wall outline, north and south of the new river mouth. This way, everybody wins.
The city gets a large waterfront park, it's practical and the cost is reasonable, the land along Cherry Street goes up in value and keeps it's views, it's a quick way to show progress on the Portlands, and will create a bold space that will be loved for years.
If the Promontories are going to be so much of a pain in the ass that the whole thing gets badly comromised - then don't do the promontories - just expand available parkland within the established boundaries. Seems like a no-brainer. Hell, use the money saved to even allot more parkland than was originally planned.
That said, I'd like to see the original plan kept. It's going to take twenty years to build out 10%-20% of the portlands anyway, so what's the hurry? Some creative financing plus things being done in phases would see it all through. But if the powers that be decide that the original plan is just too much luxury for Toronto, then we should have a compromise that keeps all the amenities of the original, or even does it one better. Doing away with the virtues of the original plan should not be on the table.