Local clients may not miss HSBC all that much (not so competitive and service levels were not great) - but no question that from an ATM perspective especially for visitors it is the loss of an important option.
Bradesco seems to be still smarting from the loss of its long-held asset leadership position vs Itau, with Itau's mega-purchase of Unibanco and would seem the most logical candidate to purchase and in fact Bloomberg has "leaked" that (reportedly) Bradesco is presently leading the bidding.
I don't want to overly tout Citi here - I would never open an account with them here for similar issues that HSBC had - but their ATM options are very helpful for visitors and residents alike especially with a Citi relationship stateside. Some of their US packages allow you to avoid that 3% conversion fee, with no additional ATM charges, and in those packages you can generally withdraw up to US$ 2,000/day per account (checking and saving count separately), which is fairly generous, just be prepared to make multiple withdrawals of R$ 1,000. Of course, there are a number of US banks that don't charge that forex fee, but I don't know, apart from the ATM limits of that institution if Citi's local ATMs impose a daily withdrawal limit or impose additional fees.