I think this is slightly dramatic.
I suspect our budget is such that anyone else coming in will be your shite loans that most of us hate. Defensive cover is a worry given Devlin's injury problems and Logan's regression. Vyner may turn out to be adequate cover but early signs at St Mirren weren't great.
Centre midfield I think we're not too bad to be honest. Ojo, Ferguson and a fully fit Bryson are a very good first choice 3, and we have cover in Gallagher, Campbell and Wright at a stretch.
Your last paragraph is total conjecture, yes yesterday we lacked confidence and looked fatigued but it's a huge leap to say all not well in the dressing room based on that. You wouldn't have said that 2 weeks ago, I think people just get over excited.
A week now to freshen up and work on things on the training ground. A quicker tempo to our play, players getting closer to Cosgrove, being less one dimensional/predictable in attack and start building some confidence into the back 4 that looked very uncertain yesterday.