Same thinking here – I don’t see any of the current generation of proposals surpassing the ~1600’ mark. Reason being, at the luxury residential market’s hottest, the tallest proposals have all been in the 1200-1600’ range, which suggests that’s roughly the point of diminishing returns.
I’m not actually sure what market conditions it would take for the next cycle to spawn even taller towers – certainly, we’re a long ways away from the skyline being so crowded with 1400 footers that a new tower has to be significantly taller just to ensure great views.
Part of the reason for that point of diminishing returns is the extreme cost of building so tall – a cost which is exacerbated by the slenderness of residential towers. And sadly, even with construction technology advancing, it’s hard to imagine building a supertall in NYC getting much cheaper.
Conversely, it’s certainly feasible to build an office megatall (see China’s many projects) but do office rents in NYC offset how expensive that would be? Will they ever?
If I had to put money down, I would bet that NYC’s first megatall will actually be a hybrid tower, with a sturdy office/retail component supporting a more slender (and absurdly profitable) residential section above. Of course, such a thing would require a huge assemblage, like 2-3 million square feet at least… although that would still be less than an all-office megatall.
As for what specific sites might support such a thing, I really have no idea. I know there was some talk of the Midtown East re-zoning allowing for residential toppers to office towers – did that wind up happening?