The New York Connecting Railroad line continues to the northeast
through Woodside before joining the NYCRR line from Sunnyside
Yards (and Penn Station) in Astoria. The line is elevated and
depressed at various points along the line as the topography varies.
The NYCRR never had station stops along the line so any stations are
even more theoretical than the Circumferential Line itself.
Queens Boulevard would probably be a good spot for another standalone
subway stop, although a station would probably need to be up on the
north hillside at the top of the concrete viaduct over the Boulevard
and the neighbors in this quiet neighborhood might not be too appreciative.