The trustee does not have to file form 8855. The trustee should be more concerned with whether the beneficiaries will accuse the trustee of negligence than he should be with the question of whether the IRS will have a problem with how long the trust has been kept open. The trustee should document his efforts to sell the property. The trustee should consult with his attorney about what procedures are available under state law to minimize the trustee's liability for declines in values of the assets. The trustee should consult with his attorney as to whether or not it is worthwhile to have the beneficiaries agree in writing that the trust be kept going and that they do not desire the real estate to be sold if it cannot yield a certain selling price.
The Trust can remain open as long as necessary in order for the Trustee to reasonably carry out his fiduciary duties. It is always a good idea for a Trustee to communicate with the beneficiaries of the Trust regarding the status of the Trust so that they know what to expect and there are no unpleasant surprises.