This answer seems self-evident, but I just want to be sure: If there are no other units on the table, the Rancor will eat itself, right?

You are correct. 

GongShowHost said:

Munch Munch Munch

It was suggested that this might actually represent the Rancor starving… but personally I find eating itself funnier.  Also note (though I doubt there is any confusion on this): it will eat itself even if there are other units if those units are vehicles or cost 5+.

Wait. Are you serious? It eats itself? That is retarded.

videinfra said:

Yes if it is the lowest cost non-vehicle unit in play as his ability is not optional since it says Forced Reaction. Just think of it as he starves to death since there is nothing for him to eat now.

But what if your opponent has a higher cost non-vehicle. The Rancor ate himself instead of attacking your opponent. I get the wording, just seems odd thematically. 

The idea behind it (to me atleast) was to prevent a munch of litte low cost weenies running around. This also would slow your opponent down when they want to play say 3PO or R2 etc, etc.

Good anti-card, not great, but nice.

videinfra said:

The higher cost card was able to kill the rancor when it attacked him.

videinfra said:

Again, thematically I'd either go with the idea that it starves or, more likely, it has no exploitable targets (either they don't exist or they're too big/dangerous to bother with) and it simply moves on with its usual routine.

If anyone reading this is familiar with the show "Supernatural", then I look at the Rancor's "suicide" as a voluntary "bibbing", as per the Leviathan leader's method of execution for subordinates that have failed him.

When a Leviathan is "bibbed", a literal bib is tied around the condemned's neck, and then everyone sits back and watches while said condemned Leviathan also quite literally eats itself into nothing.

The show always cuts away, and cuts back after the "bibbing" has concluded, where all the audience sees is a bloody bib on a chair.