Egypt - a new stage
As Egypt is a Muslim country, I assume most people in Egypt have some or many religious friends and family or they are religious themselves and as a result, quite a number of people will know some religious friends, friends of friends or relatives who were wounded or killed because of the actions of the police and army and thus anger may increase again against a force that under President Mubarak's reign didn't mind to arrest opponents, certainly if they may repeat those actions. Now the police and army claim to be on the side of the people and thus they have to prove this. While I am not in favour of religious leaders, I think it is never wise to kill people who are protesting peacefully. It is something differently when protesters use violence (maybe they did, I am not completely sure about this but they may have because otherwise why would ordinary people support something they removed from power only one year earlier although maybe people were unhappy because the economy collapsed under Morsi while there are rumours that, as the army controlled the economy, they may be partly to blame so President Morsi's government would cause anger) although even than first other methods should be tried. Still, if indeed peaceful demonstrators were shot by the army and certainly now those secret units are re-installed, some people may start to turn towards the religious (fundamentalists) and against the government. I think therefore Western countries may call for an as early election as possible so a democratically-elected president can be installed (but may not be recognised by those who lost power and thus be a lame duck) but these countries should also demand the secret units behave and will not make a mess by arresting (or killing) too many people without trial. Otherwise, in future the religious people may get even more votes and win with a larger majority.
No, violence against peaceful demonstrators can't be a solution for any government, certainly when the government claims to be in favour of the will of the people and therefore ousted the President as he was bad enough to be disliked by large numbers of the people because he mainly spoke for certain sections of society.
The government will have to talk after accepting that people who voted for the democratically-elected President Morsi have the right to protest peacefully. Only when protesters use violence the police and army can respond with some violence and then other people will accept police and army use violence to protect them. After government violence the religious may take advantage and use that in their campaign against a not-elected government, win during next elections and take revenge for the killing of friends. Only when government forces behave well can the government restore thrust. This means acting for both religious and non-religious people while knowing certain fundamentalists can't be convinced as they only want power to control people. Thus, moderate religious people should be embraced and then religious people will be able to vote for a moderate while one should not immediately assume he can't be trusted but give the person a chance. And already the army seems to be trying to speak with the Muslim Brotherhood, offering them certain ministerial posts while freeing some people. This is good, as long as the demands of the Brotherhood are acceptable and will allow freedom for everyone and not violate human rights. But the Muslim Brotherhood is not really happy as they lost most power and thus don't accept the government's offer for a joined government. This weekend may be crucial as maybe the army will stop the protest of the people. Still, I think a long fight may be ahead whereby people may face violence from all kind of people who want power, including aggression by government forces and religious fundamentalists. Revolutions often kill their best people.
Good luck for those in power because it will be difficult to keep the peace and satisfy everyone.