Needs a Boost: Can Sprint be saved, or is it dying a slow death?

Sprint posted a surprise quarterly profit earlier this week, but while the news sent shares of the company's stock up more than 10%, the news masks a much more serious dark side.  Profits were due to a boost (pun intended) in prepaid customers via Sprint's Boost Mobile, but the US' #3 cellular carrier also suffered its worst-ever quarterly loss of contract subscribers, according to Reuters.

Revenue is down, customers are leaving, and rumors are swirling regarding a third party being brought in to manage subscriber bleed.  And yet, Boost is turning a unexpectedly large profit, thanks in large part to their new $50/month unlimited prepaid service.

Which makes me wonder: Is prepaid-only service Sprint's best future option?  What do you think?