Yes, we can all madly follow Clary, Jace, Isabelle, Alec and Simon for three more books and I'm surprised a mad fan hasn't mobbed someone for the manuscript yet. Maybe because she's releasing tiny little teasers all the time, like this one from the back of the paperback release of City of Glass:
He reached past her before she could say anything, and yanked open the elevator gate. "I love you, Clary," he said, without looking at her. He was staring out into the church, at the rows of lighted candles, their gold reflected in his eyes. "More than I ever-" He broke off. "God. More than I most likely should. You know that don't you?"
She stepped outside the elevator and turned to face him. There were a thousand things she wanted to say, but he was already looking away from her, pushing the button that would bring the elevator back up to the Institute floors. She started to protest, but the elevator was already moving, the doors closing behind it as it rattled it's way back up. They shut with a click and she stared at them for a moment; the Angel was painted on their surface, wings outspread, eyes raised. They Angel was painted on everything.
Her voice echoed harshly in the empty room when she spoke.
"I love you too," she said.
- City of Glass, paperback release, City of Fallen Angels excerpt