Any unilateral decleration of statehood would result in a war with Israel and the palestinians and it could even turn into a regional war. Jordan the legitimate palestinian state 80% of its population are palestinians and if their brothers in Judea & Samaria go to war because Israel is no occupying what the UN has declared their state then they will pressure Abdullah to attack Israel. Israeli arabs may start their own mini intefadah. There are around 500,000 palestinians in refugee camps in Syria and Lebanon so at the very least Hizbollah would be involved so that means Israel attacking Lebanon. Iran will get involved just to make trouble It would be a bloodbath and the only way to achieve a ceasefire would be for the palestinians to renegotiate the borders of their state. Also going it alone doesn't solve issues like refugees, water or anything else which needs to be worked out to create a state its like having a car without an engine.
German authorities accused of playing down refugee shelter sex crime reports (Reuters)
from the article: Abbas: Only solution is to declare Palestinian state