Could be. The Foster case study of 425 Park could very well manifest (probability) depending on how much demand there is. Its in a prime location.
With a height of 483′, its kinda underwhelming. With its large floor area, I think it would be a reduction in magnitude of what it could be.
It was bought for something close to 2 billion. A hotel portion could help with the revenue, some retail, maybe even some condos or rentals, but I do hope that it is stacked even further higher. I'd be a loss of potential with this property.
425 Park or 380 Madison come to mind where they stack a new tower a top of an existing one. Manhattan has become so land restrictive bar the West Side that we should expect many more 380 Madison developments in the future.