I don't think they will go into Gaza although I hope they do. If they do not invade then the Hamas leadership will simply go underground and will re appear when safe possibly a lot stronger than they are now. When compared to the last invasion of Gaza in 2007-2008 Hamas is much more formidable than before. Before they only had short range rockets but now they have anti armor capabilities, more and better SAMs, and medium range rockets capable of reaching Tel Aviv. If you do not destroy their leadership and damage their ideology in another 5-7 years Hamas' will be even stronger when you have to factor in there are a lot more capable weapons on the black market now with the fall of Libya and the turmoil in Syria also Iran will give all they can to disrupt and distract Israel from its nuclear ambitions so even if precision airstrikes do destroy most of Hamas' weapons it will be easier than ever to get even better weapons. If I were over the IDF I would invade and wipe out Hamas' leadership. Egypt, even though they are controlled by the Muslim Brotherhood will not risk war with Israel becuase they know that Israel will kick its ass and it would risk losing the billions of aid that we give them every year. I just do no see anyone coming to Hamas' aid if war breaks out because the IDF is pretty formidable and NATO will be quick to join if Israel gets in over its head.
I do not think that Israel will invade Iran either because without aid from the US that would be a long drawn out war which I think Israel would win but if other Arab nations were to join if could get dicey. Israel knows that it can not count on Obama for military support like they could have Bush or even Clinton.