I don't believe that for a moment.
The roster has already been finalized from the beginning (with the exception of Greninja, due to a slot being given for a X and Y Pokemon character) which means that any character that has been decided to be worthy of a character slot will stay there
unless they cannot be made feasible. Which is where the Diddy-Dixie argument would normally come in. That team didn't happen because it was found out that it literally wasn't feasible and thus was scrapped. Chrom and Shulk are not the type of characters that can be compared to the Diddy-Dixie tag team in feasibility, but rather to pretty much every single character that already exists in Smash that would have no technical difficulties existing on the £DS and Wii U version.
Which is where the Chorus Men comes in. Chorus Men may be a possible example of a character that could run into technical difficulties and unlike Shulk and Chrom, are not easily guessable.
Every character so far has been correct on the leaks, especially WFT which was never an obvious choice. To get all of those correct along with the Chorus Men, of all characters, would not be any coincidence at all. If the leak got all of those characters correct, the Shulk and Chrom would have no reason to be doubted at all.