The battle system in Sticker Star is a heck of a lot like Mario&Luigi: Partners in time. Sadly I never got to play Bowsers Inside Story. I hope they do make at least one 3DS sequel. --- If you were a boss I'd deathmatch ya in a minute!
20120157196 Google that patent number and look at what comes up. It's from Nintendo and AlphaDream, the developers of the M&L series, filed Dec. 21st 2010 in Japan. AlphaDream released their latest game (JPN only) in VERY late 2009, and have been quite on what they have been up to since then. My educated guess is that Nintendo made available the 3ds dev kits sometime around then. Bowsers Inside Story (the previous game in the series) was announced less then 1/2 a year (4-5 months) before release (in JPN), so it is possible that RPG4 (if it exists) could be released in fall, or even late summer. In fact, all 3 M&L RPG games were announced less than half a year before first release. (COMPLETE SPECULATION HERE->)The long (3 1/2 - 4 years) development could be due to AlphaDream working on a different project, which got canned to go straight to RPG 4 .(<-COMPLETE SPECULATION HERE) If you didn't read that whole thing; Go up there and read it, I spent nearly an hour investigating. (>-<)
And if they do, I hope they bring back Fawful and Midbus, because that would make me so happy! ^.~ --- Call me Dawn. I'm a random fangirl who writes Fanfiction. That's all you need to know about me. :)