Oh, you mean that there'd be trains running only from Wilson to Spadina. I hadn't heard that. I'm not sure they'd ever plan that - they could just as easily do it at St. George.
They did plan to do that when the line was envisioned but the complex nature of the interchange precluded it. They put the crossover but that was all she wrote.
I do recall it was used as a terminal during the G20 for a brief period before the trains were curtailed further north.