If the highway were there the cultural epicenter would just be elsewhere. It doesn’t really matter where your infrastructure is. You need X infrastructure for Y people and development will naturally happen to take advantage of it.

In Boston they did the reverse of your example. They took a subway and moved it in to fill the void where a highway was supposed to go before it got cancelled. If they hadn’t cancelled the highway that subway would still be where it used to be. As an aside, the people who cancelled it really have a lot of blood on their hands because a bunch of major surface streets got developed into main thoroughfares as a result and we all know how good it is to have a highway speed road that isn’t grade separated from cross streets, pedestrians and cyclists…

To be fair with both the lower and mid manhattan expressway plans, they were at one point planning for buildings being built above and below the elevated grades. It wasn't just going to be dead space.