Anybody can declare a state in any borders but unilaterally declaring its existence doesn't make it real. It needs to be recognized by the internationaly and non of the countries that matter such as the US & Israel will recognize a unilaterally declared state they will all insist nothing without negotiation. Do that against US support and they risk alienating the US and suddenly they loose support from Obama & Israels left. Also if Abbas declares this state unilaterally Israel is never going to abandon its settlers leave them at the mercy of the palestinians so it will send in the troops. Instead of Israel occupying disputed land it will occupy the arab state. What happens if Israel refuses to accept the borders of this arab state? The palestinians will be in no better position to take on the IDF if they declare statehood than they will be if they don' Abbas has more to loose going it alone than leaving things as they are so he should agree to talk to Bibi without preconditions.
Prime Minister Netanyahu's meeting with security chiefs ends after four hours (haaretz)
from the article: Abbas must unilaterally declare Palestinian state