I think that the measurement of the branching ratio for ##B_s\to\mu^+\mu^-## should be seen as a test of the SM rather than of low-energy SUSY. In this context the SM seems to have once again passed this test, although the uncertainty of the result means that we still need to wait for future updates before the real picture becomes clear.
In the context of low-energy SUSY ##B_s\to\mu^+\mu^-## is a good place to find a hint, but only for some particular part of parameter space, e.g. large ##\tan\beta## etc. So the agreement of this single result with the SM expectation doesn't necessarily mean that low-energy SUSY isn't a reality, we may just need to look elsewhere before we find it.