Look at MPG to see how they common stock holders are screwing the preferred holders to get a better price for their shares in a buyout. This has happened before and BEE could give the preferred stockholders a bad deal in order to get a better price for the common holders.
I have seen it where a private company takes over and the preferreds are no longer listed except in the pink sheets. It is also possible that as a private company, they would not pay the dividends at all and let them accumulate, since there is no reason to pay them unless they wish to also pay common dividends. A private company may not pay dividends on the common. Lastly, as was mentioned, it could be bought in an LBO and become a very leveraged REIT with a higher risk of default.