Not so fast. People have said this about gittip (now Gratipay), Patreon, Twitch, and now YouTube and Facebook. All of these have been mixed blessings. Here's an article about how Patreon doesn't work out even when everything goes smoothly:
https://theoutline.com/post/2571/no-one-makes-a-living-on-pa..."After launching my Patreon, I struggled for months to find work. Patreon filled my downtime, and became a full time job itself. I’d spend hours combing through photos, looking back on notes I’d taken on the road, researching where I’d been. I’d post on Twitter and Instagram with teasers, free stories, anything to attract my followers to my Patreon page. I made friends on the site, I shared their projects on my own social media, and kept up with all my subscribers’ projects. It was a lot of work for little pay, but I was determined. A year later my monthly earnings on Patreon have grown from $120 to $163."
$163 a month in extra income? Cool, right? Not when you spend 5+ hours a week thinking about it.
If GitHub gets a lot of participation it will be unsustainable to only take a little on top of a credit card processing fee, and the fee it will be increased to be more like Facebook's 30% cut. There are plenty of articles on here about the costs and difficulties of running a payment platform.