Way, waaaaaaaaaaaay back in April 2013 (>>2128517), reader The Hittite was the first one to guess that it might be Prince Blueblood. (To jokingly guarantee his elimination from the lineup, perhaps, but a call is a call.)
And unlike some many situations in this comic series, this isn't the result of improvisation or changing to a better idea at the last minute or following guidance from the comments section. No, from the moment Elusive was name-dropped, this was always the plan.
Speaking of thieves, we finally recorded another episode of that campaign podcast involving thieves! Dusk City Outlaws Session 6 — The Seven Seas Job, Part 2: LibsynYouTube
Transcript: (beat) Rarity: You're Elusive? Blueblood: Yes. Don't be so surprised– Rarity: YOU'RE Elusive?! Blueblood: Yes! I already– Keep it down! We're in a public– Rarity: YOU'RE ELUSIVE?!?