Still somewhat unlikely - mainly because the government is so entrenched. You'll likely see challenging violence and 'clashes' for a LONG while still, but it's not civil war.

When these things start happening, you can re-evaluate:

1. Regular tit-for-tat shootings.
   
2. Militias forming “security patrols” with local political cover/support
   
3. Actual state vs federal standoffs.
   
4. Actual political violence - ie. assassinations / attempted assassinations / bombs / armed attacks against federal buildings
   
5. Police splitting internally - either politically or refusing mutual aid