This is an interesting distinction. I heartily agree with your emphasis on the importance of paying to post in a forum. It's possible that the reason most of the great internet forums have gone extinct or been turned into monsters (looking at you reddit) is because they couldn't figure this out.

My fear with v4v is that it will not amount to enough of an income stream for content creators and that they will have to look elsewhere: ads, paywalls, subscriptions.

I'm not saying posting on a forum should result in a full time income, but I am very much uncertain about the role v4v will play in actually incentivizing really good content.