The Israelis have stated several times that the ideal Syrian scenario for them would be for the fighting to continue as long as possible.
And it is only in their interests if their neighbouring countries become unstable and busy with internal violence and chaos if the jihadis spillover into Lebanon and Jordan.
This will deplete those countries’ military capabilities, and potentially create even more catastrophic conditions that will require “humanitarian military intervention ” , and this will just break their neighbours into little pieces.
The jihadis will burn a circle around Israel and the Israelis will march over the ashes to expand their state on the ruins.