This isn't a terrible idea, but I think it belongs in the header (maybe meta tags) of the page to be loaded. Then if you added a paywall to your site, you'd update your server config, rather than trying to round up every hyperlink to your site ever. Imagine if Chrome could do a HEAD one link deep, and indicate visually whether you'll actually be able to see the page, or whether you'll be solicited for some personal info.
In the meantime, someone could write a Chrome plugin that uses a blacklist to rewrite links to paywalled sites.
Yes, but they have no real incentive to put them there, since they want people to see the paywall (and possibly subscribe). Besides, many paywalls are dependent on the user (e.g. she may have some free views per month or so).
In the meantime, someone could write a Chrome plugin that uses a blacklist to rewrite links to paywalled sites.