Maybe they'll offer it as a stretch goal. But it does take a lot of time/effort/money to translate thousands of lines of dialogue into another language. It's not likely that Larian has off-hand someone who can speak/read/write Portuguese, let alone Brazilian Portuguese (which for all intents and purposes, might be similar or even the same thing).
I wouldn't get your hopes up, but you can always suggest your thing here: http://larian.uservoice.com/forums/313815-kickstarter-pledge-rewards
where all of the Brazilian fans can vote on whether or not they want the translation to be part of the kickstarter.