Speaking out of pure ignorance, I suppose everyone's waiting to see what the army does next. In Tunisia, the military identified and sided with the civilian protesters-- but at Tiananmen Square, the Chinese government very deliberately brought in provincial troops (and provincial kids) from the Chinese equivalent of Alabama. They told the soldiers that the Tiananmen demonstrators were dangerous radicals, hippies, college punks, commie reds (what does a communist call a commie?). Thus, Chinese soldiers very cheerfully gunned down Chinese democrats.
I've no idea what social class Egyptian cops and soldiers come from, whether they'll support their neighbors or the government. Looting is breaking out, as well as attacks by agent provocateurs, and that works for a dictatorship, not against it.
In our own country, I suspect our military class is becoming more and more segregated from the people and the Constitution they are sworn to protect. This was part of the dynamic that led to the shootings at Kent State. If push came to shove between Fox News Corps and a serious progressive reformer, does anyone want to guess which way the American military would jump?