Yes and no. Quadrant 37 specifically - possibly not - but something similar would have happened.
The Shadows wanted to start causing chaos - their philosophy of promoting change and growth through conflict. This was made explicit in Into the Fire in season 4:
"It is the cycle," Lennier explains to her. "It is the force of
history itself. You cannot win against that. We have embraced it.
We've helped it along, by creating conflict. Weak races die. Strong
races are made even stronger. Evolution must be served. There is no
other way."
They were looking for both a race and an individual that they could manipulate to promote this a couple of episodes prior to Chrysalis in Signs and Portents, where Morden was asking the question "What do you want?" Londo gave an acceptable answer, but other responses would also have done, if they indicated the individual would be open to manipulation, as per JMS comments:
There would have been more than one answer that would have sufficed,
but one answer was better than all the rest. Just the right mix of
resentment, nostalgia, ambition, frustration and a sense of displaced
destiny. Londo was hitting all those cylinders when he answered
Morden's question.
The Shadows were not going to give up if Londo didn't succumb to temptation. They would have either continued to push him, or found someone else to work with, and the same or a similar attack would have happened.
