The chances of marth's smash character being totally re-written to keep in line with a DLC chapter that was made to exemplify their characters similarities and hide their clear differences... is pretty unlikely in my eyes.
In terms of Tiki, she mainly commented on the similarities in the way she acts with the other units (around the campfire) and how she can pull people together... she never makes comment of her sword-style to my knowledge, though Tiki likely isn't the best judge of swordsmanship anyway, so I doubt she'd be the best source for that. In fact the only mention I can think of is a comment about how Chrom and Lucina's styles are similar.
It might happen, but it would be a bit disrespectful to Marth to give him a Lucina move set because of one game, and ignore his previous one, or to give Lucina Marth's move set when hers should be different.. Especially if they put Chrom in, who should have the same moveset as Lucina.