What will be the outcome?

Nobody knows for sure of course, but the number of demonstrators on the street can give Iranian demonstrators unfounded tactical optimism as I felt 20 years ago on Tian'anmen square. No matter how many million people are out on the street, and how determined they are to fight to the end, as the citizens of Beijing were back then, if the government wants to use real force, there will be completely unbalanced unsustainable fight. If it comes to using tanks and machine guns, the only chance will be somehow most of the troops are convinced that shooting or running over unarmed people is an order that can absolutely NOT be carried out.

After seeing Tian'anmen square, military personnel during many mass demonstrations in 1989 Eastern European countries like Romania felt that what they saw on TV a few months ago should not happen in their own country in any case. They'd rather shoot the dictator like in Romania. Maybe reminding everybody of the bloody and horrific street scenes of the Tian'anmen event will be helpful to prevent it from happen again, anywhere.

watching cnn, remembering 20 years ago

This time, from a distance. The show of number by people, the quite period of the power, then the characterization of the movement as against the country, and "western power backing" routine with no details(still no such foreign meddling was eventually shown by evidence 20 years after it was used as one of the reason for cracking down in Tain'anmen square), the escalation on the street.

Iranian people are brave, determined, and very smart. The rooftop shouting at night, the changing of tactics for demonstration, and continuation with communication channels clamped down and clear leaders missing, god I didn't think I'd see history of such scale happen in front of my eyes again in my life. Justice and people's rights will win in the end.