In reply to James Britt.

Just wanted to follow up that I've had a bit of interaction with Disqus support. IMO, the plan they are proposing looks pretty reasonable. i.e.:

Only higher traffic, commercial sites are subject to the ads.
For those that are subject to ads (to remove):
less than 50k pageviews is $10/mo
less than 250k is $99/mo
more than 250k will be contacted re: pricing

So, kind of like using a host like WP Engine, if you're commercial and getting those levels of traffic, you *should* be able to monetize enough to cover costs, I'd think.

Also, they insist they notified the sites that got ads, prior to that talking place. It does seem a bit of a cart before the horse to roll it out before pricing was firmed up and launched, but it doesn't sound like, one day, it was just *surprise* ads, either (unless Disqus is lying).