Entirely unpredictable at this stage. Could be confined to BKK: action elsewhere won't affect the senators & the authoritarians much.
Any protest activity could turn violent but it will be ineffective if not well-planned. Needs action with military precision and including bringing the lower ranks of the army onside, in & around BKK ... Needs to choose targets carefully - airports, individuals & their homes & other known assets ...
Probably beyond Thai capabilities to organize, but who knows?