Syria isn't suicidal to get itself directly involved unless it's in retaliation.
However, if there are long-range rocket attacks from South Lebanon tomorrow [as feared] then Israel may hit some key targets in Syria, which in turn may get a reaction and so forth.
It's an unpredictable and dangerous situation. More than likely things will simmer back down in a few days after some air strikes and ground incursions back to the relative chaos, but theres a possibility of an actual regional conflict if things get out of control.
Israel must have a relatively pacified Lebanon always, but if this is to expand to include Syria, Lebanon is vital. Iran, who knows.