[myname].com v. [myname].tumblr.com

Quick question, Tumblr Hive:

For the longest time, I’ve been hosting my Tumblr blogging account (jasonpermenter.tumblr.com) elsewhere with a custom domain name (jasonpermenter dot com). Am I right in assuming that if I click the button and revert back to using “jasonpermenter.tumblr.com” in my Tumblr settings, all the previous external (incoming) links, reblogs, &c, associated with my blog will break?

Anyone have any help/comments/suggestions/advice before I brazenly take jasonpermenter dot com back for other purposes?

UPDATE: Thanks you guys! I’ll let you know when I make the switch, just in case. But it looks like it’s totally possible with the mod_rewrite fiddling, as TJ explains.