There is no chance of Monarchy returning to Iran, the people of Iran would not accept it any more, it has to be a Republic but a Democratic Republic and a secular system.
The Shah was brutal also, I agree with ali_europe, but the current situation is different from 1979, I was in Tehran in 1978/79 and attended a lot of demonstrations (I was 14/15), what I see on utube somehow scares me more than what I saw in 1978/79 did, this is somehow different, in 79 the civil war lasted some 48 hours, if the opposition take up arm now then the fighting will go on a hell of a lot longer, could be months, the Basij and Pasdars will not surrender the way the Shah's Army did, only Shah's personal guard (Javidan) fought to the end, the others changed side, this will not happen today, Ahmadinejad does have a lot of supporters whether we like it or not, they might not be in the majority but they are brutal and heavily armed.
Afshin jan I absolutly agree that today conditions are different than 79 revolution...IRAN has today 78 million population..and unlike Shah which was fully dependend on foreign powers IRI has a base of conservative supporters among revolution guards but also among 4-5 million IRANIANS (Bazar, religious families, etc)
that's why it is very important for the opposition movement to keep continuing with pressure on governments for more freedom and democracy but at same time keep the movement united and not allow any slogans which would create tensions between different part of reformers...
For example now would be really not smart if for example Kurds or Sistanis would just start with the anti-Persian slogans or if the liberals and leftwings would attack islam as a religion.... I think right now all those who want changes must stay united and keep the pressure on IRI and focus on freedom and democracy issue, till IRI would be forced to go some steps back...... at same time that would keep a door open for those members of pasdaran or religious people, who would be ready to talk and accept to allow the demonstrators to talk on major questions in public and find a peacefull solution