Is the de facto opening of the border between Egypt and the Gaza Strip a danger to Israel? In the short term, of course, it will allow an influx of weaponry and even terrorists into Gaza, with predictable consequences. Similarly, the rise of Hamas as a political force in Gaza seems to bode ill for the prospects of peace in the region.
But in the long term, the real problem is more basic: a horribly overcrowded, economically hopeless, implacably hostile and violent enclave adjacent to Israel. And there really is only one plausible solution to it: the voluntary emigration of large numbers of its residents.
As long as the Egypt-Gaza border was closed, and a nominal PA government held out the hope of relative calm in Gaza, emigration was fairly difficult (hindered by Arab countries not eager to absorb Palestinian refugees), and the inflow of international aid, combined with Israeli restraint, made life there just bearable enough to keep residents from fleeing in droves. However, the ascendancy of Hamas, with the resulting escalation in violence--which will make life distinctly more unpleasant for Gaza residents--and reduction in international aid and support, together with the open border, may be enough, taken in combination, to get the needed exodus started.
Now, lest I be misunderstood, I'm not advocating ridding Gaza of its Arabs, or even of its Palestinians. Rather, my point is that Gaza's terrorist infrastructure (effectively tolerated by Israel) and international aid spigot are keeping a population there that otherwise would long ago have begun decamping for more promising locales. The trapped residents, however, end up with no opportunities beyond terrorism, because that is what the people who control the money and the weapons want. As long as Israel lacks either the will or the means to destroy Gaza's terrorist infrastructure, its only hope is that the flow of international money eventually gets cut off, the terrorism ends up damaging Gaza itself more than Israel, and an open border then allows residents who have lost their reasons to stay, to leave.