If the 30,000 expected show up to protest it won't need to be hyped, just reported.
People were claiming 100,000 just two days ago.
And it will be
reported no matter what. (Even the RNC protests were reported.)
But it
will be hyped no matter
how many show up.
It's the only "interesting" story, which would be enough on its own.
That "Harris/Walz has all the momentum" is boring is another reason to find anything to counter that narrative and the general pro-Trump desire of the legacy media is going to feed into that.
The real issue is violence.
If they can get violence, they've got a
real news story.
The media is still
very angry that they didn't get their thunderdome convention.
Riots in the streets is the next best thing.
You've got "echoes of '68", you've got "Dems in disarray"... it's great.
The people who want to discredit the demonstrators also have lots of incentive to paint them as violent as well.
Any conflict between the cops and the protesters will be hyped to high heaven.
(That isn't to say there isn't a real possibility of serious violence that rises organically - there absolutely is whenever you have protesters and cops in a US city.)
There are
lots of incentives on various sides for people to start something and for the press to make sure it is treated as the main story.