Israel is already passing laws to make it much easier to expel anyone from the country (in the past two weeks). If they annex the West Bank and/or the Gaza Strip, they will have the "legal" right to enforce their laws upon the people in the West Bank or Gaza Strip. If this were to happen, the "boil over" in the Middle East could turn into a full scale "eruption".
UN chief condemns Palestinian toddler killing, urges calm (Reuters)
from the article: Israel needs to launch a preemptive diplomatic strike