This is just another bone thrown to the reich wing dumbass's.
Look until there is a LEGAL description that is written by congress as to what a Sanctuary City is--nothing is going happen.
Without a legal definition as to what is a Sanctuary city--there is no way to determine which cities are sanctuary and which ones aren't. This has to be written by congress, voted on, then approved by the Senate and then signed into law by the POTUS. If there are going to be fines or people are going to go to jail, Congress would then have to right another bill about that "what to do with Sanctuary Cities" after they define it LEGALLY.
Until then it's just another right wing buzzword to send you all into a frenzy.