You’re not really stranded, it’s just that Bklyn bound 2,3,4 trains are not stopping at Bergen Street, Grand Army Plaza, or Eastern Parkway. You can leave the Slope but it’s difficult to return from Manhattan.
And if you’re expecting guests let them know that they can’t get out at these Slope stations. They’ll have to go to Franklin Avenue and circle back.
Check the service advisories at the MTA website to verify this.
This is the second weekend in a row for this GO. Somehow, I think Slopers will survive. Try one of the other four subway lines that services the area instead.