Thanks Dash,
Since WN got LGA they have expanded there and reduced ISP accordingly. I'd assume this logic is also at play with US dropping ISP-DCA as they probably want to force people to use The shuttle, but I'm not sure that will work.
In any event WN is down to less than half the flights they had at their peak, and even dropped ISP-MDW which was a popular route. I think an E175 to ORD or CLT would work now, as there really needs to be a legacy operating out of ISP. The airport is like a ghost town lately.
Hope you are well.