Definitely different from earlier days, but still viable source I know a few personal mates doing well on it still!
It is of course quite technical, but the optimising process is a fantastic way to learn affiliate marketing. The evergreen niches finance, dating, weight loss, gaming still do incredibly well and leadimpact/trafficvance are still top 2 sources as far as I know. Just current competition is quite hardcore and I would imagine the bidding wars on those verticals would be tight hahaha
But yeah definitely still a viable source of income for any aff marketer