Israel will use Sunni extremists to infiltrate from Syria the Southern part of Lebanon with the intention to weaken Hezbollah. Aggression and violence has to be expected mostly in the South of Lebanon and Beirut.
A little bit later Israeli Forces will start a directly or undercover war against the armed Force of Hezbollah. Sunni fighters will most probably not know that they are used by Israel.
Lebanon will find itself under pressure in a very short period of time with two conflicts: from the east with Sunni fighters and from the south with Israel.