While I could be wrong, I quite doubt that any action by the US Congress would support Microsoft's position in the matter. Their best, probably only hope, is in the possibility that the Supreme Court will allow the second circuit's decision to stand. The issue, overall, is fairly complex owing to the possible permutations of jurisdiction over the crime, the suspect, the data storage operator, the data storage facility, the legalities surrounding operation of the storage facility, and numerous other things. Orin Kerr has written extensively on the Stored Communications Act, including several pieces in the Washington Post Volokh Conspiracy blog, that are worth reading.
The Second Circuit's analysis primarily addressed the law as written, and may be correct; as a non-lawyer, I do not feel competent to judge that. Its reasoning, however, points the way toward legislation that would remedy the problem, for US courts, by making clear that the provisions apply to stored communications in facilities under direct control of companies, like Microsoft, that operate under US jurisdiction or do business in the US. However, such an extension would be difficult or impossible to enforce on companies that contract with non-US companies, possibly including non-US subsidiaries, subject to foreign governance, for their off-shore data processing.
In the end, this type of search probably is best handled by refining (or if necessary establishing) mutual legal assistance treaties. No country is likely to be pleased by the idea that their criminal investigation may be thwarted by the unintentional actions of a third party like Microsoft in choosing, for its own business purposes, to store customer data in a particular data center. The Second Circuit, I think, misconstrued the technology at the time the SCA was passed in 1986, but technological change since then certainly has reduced the significance of national boundaries in data processing, to a degree that almost certainly warrants MLAT renegotiation in the subject area combined with coordinated legal changes in the respective countries.