Serebii said to not look into that quote too much.
Prepare to be disappointed.
But apparently it's a new "battle mechanism", according to Masuda. http://www.gamefreak.co.jp/blog/dir_english/
It must be of some importance, otherwise I don't see why they would talk about it.
But this is coming from a series that's been stressing the significance of trainer/Pokemon relationships since day one. Another repetition of the same message isn't going to have a big impact.
It's probably GameFreak just revealing the existence of Effort Values; they may be calling it "new" because they never officially went public with that mechanic before. Or if it's not that, maybe it's something similar to the system that Conquest had; maybe a notable increase in stats. For instance, a Level 40 Pokemon with a maxed-out bond might be as powerful as a Level 60 wild Pokemon. It'd be convenient if that were the case, because then you could fight much stronger Pokemon for more experience without being at a great disadvantage.
U say U want a Revolution Well, U know Wii all want to change the world