This question has come up a lot recently because people fear that the Olympus camera business will be shut down or acquired. The company is most certainly under huge stress now, and the entire board (which includes many members of the executive team) is implicated in what's happened. After restating their financial numbers for the past five years, undergoing an external audit (though by people appointed by Olympus), and generally admitting to what happened, the actual fraud is mostly behind them. The issue now is clean up. We're likely to see investment in Olympus by another Japanese company and/or banks to shore up finances and give them some operational breathing room.
The worry when you buy into a system is that the system won't be around forever, thus upgrade and updating options will go away. Unfortunately, the risk of that isn't zero for any system. The scandal increased that risk for Olympus aficionados, but probably only minimally. Plus, Panasonic shares the m4/3 mount, so you could always just replace your Olympus bodies with Panasonic. So while there's risk, I judge it to be a very low risk overall.