I can imagine websites refusing to link and instead displays the URL so the user can enter it themselves.

A lot of new companies will pop up offering their LINKTAX compliant packages that offer automatic downgrading of off-site links to user-selectable link fields, some even with custom functionality to automatically place the link in the clipboard.

Tech savvy users will use adblockers to disable this auto-delinking script.

All uploads will go through the few behemoths of media that can implement the upload filtering, like YouTube.

User uploaded profile images will be substituted for generated images by the website.

Uploaded text content such as comments will be disabled for all but the websites that live off them. Get used to seeing "Your comment is not currently visible, but awaiting moderation".

What a miserable, sad web...