I think such a toggle is old-school. The real future would be an embed that asks every time. That is, you as creator choose something like always, never, ask-me (either site-wide or per-post, preferably a site-wide DEFAULT, with a per-post override). Ask-me would send you a notification (think WordPress moderated comments) and you check the embedding site to allow our disallow the embed.

What I like about embeds is that the creator maintains control over whether the content remains on the web, and it cannot be modified. What I dislike is that it can still be used in ways that don't credit the creator of in ways the creator may disprove of, and in almost all cases, the benefit is primarily/solely going to the embedding site, because no one (or a miniscule fraction of total readers/viewers) clicks through to the source if they can read the content then and there.