I honestly don't see much of a reason to take this very seriously.
1) It's a translation of a translation of an article that we have no scan of. Not exactly the most reliable source.
2) We have had false translation rumors before. (Recall the whole Animal Crossing fiasco, if you will.)
3) "He also said there will be many playable characters, more than you can imagine..." This doesn't exactly sound like something that Sakurai would say based on what we've heard from him. He's usually very humble and cautious with information. He has never said anything like "there will be more characters than you can imagine"; he'd be more likely to say something like "we're doing our best to include as much content as we can and I hope you will enjoy it". Even if the article is theoretically somewhat legitimate, I sincerely doubt this part of the translation is accurate.
4) "...and he said the team is still adding and programming characters." This is what makes me most skeptical. I can't profess to know everything about the development process here, but I have always assumed that testing and balancing characters was a much more complex and time-consuming process than just putting them into the game. I sincerely doubt that the delay was intended to add characters; It was probably more to fully test and balance the characters already in the game and add other kinds of new content (like the random kinds of modes he releases every now and again). Two months of development (minus the time devoted to production and shipping) is not a lot of time. I sincerely doubt they are adding in totally new characters from scratch at this point.