Israel has the capability of annihilating the Palestinians but lack the desire. The Palestinians have the desire to annihilate the Israeli's but lack the capability.
2015 Israel Military Strength
More like if Israel annihilated the Palestinians they'd soon be under UN occupation. Don't pretend Netanyahu isn't itching to pull the trigger.
If Israel decided to annihilate the Palestinians it would be over in less than two weeks, using conventional weapons.
Nowhere near enough time for anyone else to respond, effectively, militarily.
As to the UN, well...
That Old Lady's Debating Society hasn't shown a set of balls in a very, very long time, about damned-near anything...
And, UN intervention would only be possible up to January 20, 2017, after which time, the US would once again veto any such proposal, almost automatically.