Note that AoC has been consistently undervalued by Funcom:
In 2013, AoC's book value was only USD 247k, but FC noted in their annual report that "the impairment test performed at the end of the year demonstrated that the recoverable amount of the cash-generating unit Age of Conan exceeds its carrying amount by USD 2,000 thousands".
In their 2014 annual report, FC noted that "The performance of the game remained stable in 2014 and the impairment test performed at the end of the year demonstrated that the recoverable amount of the cash-generating unit Age of Conan exceeds its carrying amount by USD 944 thousand."
So clearly there is some limited upside potential for a company willing to invest into the game, even without major new development or marketing. The real question is how much a potential buyer would have to invest to build on that potential. Red Thread Games probably would find it easier than others to take over AoC, but I doubt they would want to bother