I'm starting to think Lucas may be the only character cut. Think about it:
-He's almost a 1:1 clone of Ness.
-He wasn't very popular in Brawl.
-He represents a series that really only needs one character, and that character is a 64 veteran.
-Compared to the rest of the characters at risk, he has less reasons to stay. Take a look:
^--Wolf is a villian character and a worthy addition to the roster.
^--Falco is a Melee veteran, the best 2nd rep for Star Fox, and while a clone, was Luigified in Brawl.
^--Jiggs is a 64 veteran and is semi-popular in Japan. See my earlier post for more on her.
^--Ike is now a reoccurring Fire Emblem character and has a unique moveset.
^--Snake is a 3rd Party, has a unique moveset, and has no real reason to be cut.
^--Pokemon Trainer is important to his series and has a unique moveset.
^--ROB has a unique moveset and represents the entire NES era.
On the other hand...
-He's the most recent Mother protagonist.
-Cutting him would actually shrink the series' total characters.
I think the order of priority, from least to greatest, is roughly this: