In part, yes. We can still get out but it would take much longer to travel the galaxy without the relay.

[But her question will make Liara pause and think for a moment. Rally the mercenaries and the rest of the local populace. It was a long shot but if Aria managed to do it against Cerberus then it might be possible to rally others together.]

No, it's not like kingdoms at war, it's closer to fighting against bands of deities. I'm not sure how you'd go about getting mercenaries to fight reapers, no one has that much money, even if some of the gangs may be running scared because of the news about Thessia.