Personally I don't consider this a significant event for long-term holders. The investigation into the options will play a moderate role in its long-term stock performance but quite frankly I couldn't care less if it's part of an index. In the short-run, of course, you could and probably will see some pain if it's delisted. The fact is though, Dell was handed a similar warning today so I wouldn't be too concerned.
If anything, I would consider delisting a long-term buying opportunity and would welcome it as the risk/reward at $14.50 is still a bit steep. Not that the company isn't going to go up, I believe it will, but you just have too much potential downside at $14.50 for it to be a "good" buy. For the record, I got in at $10.61 and am going to wait this out.
Ultimately, I believe the largest factor in this company's long-term performance will be it's profitability. It has not been profitable of late. However, as I pointed out previously, video game developers make essentially all of their profits in the Christmas quarter. Last year's Christmas quarter was heavily affected by the GTA sex-scandal, again see my past article. This year's Christmas quarter is basically a clean slate with a new release of games.
The company has delivered hits in the past and will probably do so in the future. Your hedge (it's gotten a lot smaller at recent prices) is that the company is selling at a fraction of its past revenues while competitors sell at multiples of 2-5x. Keep it on your radar screen.