NEW YORK ( TheStreet) -- In order to survive in the investing world, and on Wall Street in particular, sometimes it becomes necessary to contradict yourself -- or at least have certain offsetting viewpoints.The reality is, if you are an investor and you are not mired in a state of perpetual worry, then you are probably not paying attention. "Conviction" is overrated. This seems to be the case for Pandora Media ( P) and Sirius XM ( SIRI) as they appear to be stuck in the constant dance of one step forward and two steps back. For as well as Pandora has performed of late, it seems inevitable that tech giant Apple ( AAPL) is poised to take over its territory. Apple has yet to make a formal announcement about its streaming aspirations and the rumor alone was enough to send Pandora investors running for cover. It is premature to say that Pandora would not be able to coexist with Apple if it indeed decides to pursue streaming, but when have we known Apple to be pleased with second place? Apple is not new to music. What's more, the ease with which its existing mobile devices such as iPods, iPads and iPhones can integrate with IP and within the automobile will render Pandora irrelevant in the manner that CDs have become archaic. People will be able to stream their existing songs on to various platforms all from their existing storage on iCloud. What will then be left for Pandora besides becoming an attractive acquisition target? I can see Google ( GOOG) or Microsoft ( MSFT) becoming interested, but will they be willing to pay more than what the stock is currently worth? As much as I enjoy listening to Pandora, it is hard to see that the company will have a sustainable future if/when Apple decides it wants its business. I think the stock is a sell. For similar reasons, I have become somewhat concerned about the prospects of Sirius XM ( SIRI). However, Sirius' biggest fear at the moment has only to do with the challenge it faces against Liberty Media ( LMCA) who wants nothing more than to take over the company.