Personally, my "holy grail" is a website that lets AUTHORS monetize their product using the site's ad network. If I upload a video, I shouldn't HAVE to pick the ads that run as pre, mid, or post-roll, but I should be ABLE to. I should be able to make my own deals, on the platform, with advertisers participating in that network. Essentially, the site should act as a facilitator between advertisers and content creators, rather than the programming scheduler. For providing this facilitation, the site should be entitled to a small percentage of whatever deals are struck.
Once the network is established as a good place for creators to be able to actually make money, you attract the good creators. They aren't getting pennies on an ad (or, if they are, that's what they were happy with; we all start somewhere/traffic volume is important); they're getting the full ad buy minus some percentage for the site (more like 10% -20%, less like 50%-90%).
As the site, acting as a publisher, you get to dictate the ad network, and set boundaries for keeping things profitable (neo-hayes-code "cost of doing business" gatekeeping). As content creators, they get freedom of association and deal-making (which includes refusing to serve ads that they disagree with).
Then, when you have a solid network of solid content, you layer in a subscription model which could allow you to sensibly bundle content. While each content creator could set their own subscription tiers (including free ones, for the purposes of advertising their own content or giving things away for free because they are such absolute champions), they would be able to opt-in certain tiers to be "bundled", which would allow users to pick and choose content creators that they want their subscription bundles to apply to.
This is where you get to the first rumblings of reasonable payment for journalism work. Because, as far as I know, it's almost impossible to get people to pay for journalism, no matter how good it is. But if you can add it in to a bundle, while still letting people choose their outlets/sources, you can subsidize the journalism with the media profit (like how we do it on TV).
Of course, to facilitate that, the site would need some robust utilities for writing new articles, such that it might be indistinguishable from a WYSIWYG website creator, but that's not something that's insurmountable. Especially if the site is profitable.
Anyway, that's my swing. I've been working on it, myself, but it's not like I ever intended to run a social media app. I certainly don't have the funds to run it, myself, and it's an untested model so investment would be very surprising. So just POC stuff and collecting feedback from content creators. It all seems very promising, but I still haven't answered the question of 'will it make money?'