I'm sure there's still money in affiliate programs. However, the "big money" seems to be in stuff that didn't even exist a few years ago. For example, the more popular Youtube "celebrities" get paid tens of thousands of dollars to promote a single product. Ditto for those with huge Twitter or Instagram followings - they can make what most people would consider an enormous amount of money off a single promotional tweet or endorsement. That's because they bring to the party what many companies struggle to achieve: a ready audience. Now other things are hotting up: Snapchat, Periscope etc. But the mantra's always the same: "eyeballs - the more, the merrier".
But basically, anything that brings a huge volume of traffic can be monetised in some way - just witness the rash of fake news sites, and "funny pictures/videos" sites (which all seem to pirate each other's content) that have sprung up recently. Even if they can only scrape together a pittance from ads because they're so junky and unfocused, a million pageviews at $1 CPM will be $1,000 a month (and some have tens or hundreds of millions of page impressions a month)
Equally, I'm pretty sure you can make good money if you go "niche" but put in the hours to become THE authority in that niche. For example, StorageSearch.com. It's not a particularly pretty site, but over the years they've put in a vast amount of effort to be THE site for news about developments in SSD technology - and I'm sure their mix of sponsors reflects that.
Re. parking and sales pages, it's important to consider the reason the domain's getting traffic...
A) If it's an expired site with old links, a typo of a popular site, etc.: park or stick relevant affiliate ads on it (or even redirect straight through an affiliate link if you can find an affiliate program that allows zero click). It's almost certainly not a generic domain, so domain sales aren't going to come into the picture.
B) If it's a completely generic domain that's getting type-ins by virtue of its genericness (i.e. people typing it in "to see what's there") then:
- If there's just a dribble of traffic, then have it all go to a domain for sale page (you're likely to make pennies from parking, and one sale could net you thousands of times that)
- If there's a good amount of traffic, then park it with someone that also allows you to put a note on it that it's for sale