IANAL, either, but here's how I see it...let me use an analogy or two.
Say the US Congress passes a resolution to consider Saddam Hussein an ally...but then Saddam invades Kuwait. Does that resolution mean that we have a treaty and can't back out of it? No...it was an internal decision regarding our posture toward someone.
Likewise, as I understand it, the $1 idea was a resolution passed by the City Council, but it was not put into a contract, perpetual lease, etc. Therefore, the Council may simply change its posture in light of its view of SCOTUS opinions.
No doubt this is politically motivated; doubt that there's truly the SCOTUS backing for this. But regardless, I don't think that this can be fought on the idea that there is some contract being broken. But again, IANAL.
Ninety percent of the most powerful lawyers in Philly are Democrats. This is a lost cause and a tragedy.