I'm planning on recreating all of the Licids, with slight tweaks when necessary to keep them within modern design sensibilities (e.g. changing fear to intimidate). The best part is the huge amount of flavor text they now fit!

Question: should there be Licids on Mirroria, or should I create a new, Licid-like creature type?

My instinct tells me to use Licids. In order to A) Drive the point home and B) reserve new and wacky creature types for new and wacky mechanics. As it stands, Licids do a good job of making some people feel comfortable with super transform set, since they do an excellent job showing how transform can give some cards some leg room. Making them a new creature type distracts from that.

Also, yay for Licids! Personally, I thought the abundance of Licids in Tempest block was a little broken, since they've got a Regeneration/Lifeline thing going on. People always seem to forget how good these things are when they block... and that was before the 6th edition combat damage stacking rules applied. They were never a big part of any tournament scene, but I'd be careful with limited. Wizards never tested for limited back then, and a 'blinking' creature mechanic could get messy.

That is impressively succinct, I have to admit.

Flip side should be named "Illicid control" Scary unkillable blocker that throws your other creatures in each others way. argh.

Yep, that's just what Dominating Licid was as well.

Might need to be quite a bit more expensive and/or rarer, though. This is a very powerful effect.