Protesters are already facing threats of physical violence, so saying that there won't be overt military action isn't likely to change many minds. Dozens have been injured in altercations with the Hong Kong police department since protests started last month. There have been several accusations of police brutality, coming from both protesters and journalists. There are also accusations that the police are already using the PLA or other forces from the mainland to bolster their ranks, but it's hard for me to tell how likely that is too be true. The primary pieces of evidence that I hear are officers covering or wearing incorrect identification numbers, and officers speaking little/no Cantonese & speaking Mandarin instead.

Not sure the protesters would do much differently until they saw military action, or lack of it.

I don't think a news story changes much.

Which would then give them an excuse to send in the military.