Are there published predictions that hydrogen could remain metallic at ambient pressure?
According to http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/pdf, "Brovman, Kagan, and Kholas showed that hydrogen would be a metastable metal with a potential barrier of ~1 eV. That is, if the pressure on metallic hydrogen were relaxed, it would remain in the metallic phase, just as diamond is a metastable phase of carbon. However, Salpeter showed that the metastability time of hydrogen might be short due to a tunnelling mechanism in which atoms on the atomic lattice tunnel into molecular states. Since metallic hydrogen is yet to be produced in the laboratory, none of these ideas have been tested." The relevant references are
Brovman EG, Kagan Y, Kholas A. Properties of Metallic Hydrogen under Pressure. Sov Phys JETP. 1972:783-7. Salpeter EE. Evaporation of Cold Metallic Hydrogen. Phys Rev Lett 1972;28(9):560-2.
I did not read the references.
EDIT:(01/28/2017) Reference  is at http://www.jetp.ac.ru/cgi-bin/dn/e_034_06_1300.pdf Abstract: "The properties of metallic hydrogen at atmospheric pressure are considered. The problem may be of great theoretical and practical importance. Perturbation theory is employed, which previously was successfully used for analysis of nontransition metals and which takes into account electron-ion interaction up to the third order inclusively. In the given case third-order terms were found to be very essential. It is found that metallic hydrogen tends to crystallize at P=0 into sharply anisotropic structures. This tendency in turn leads to the existence of a whole family of structures with very close energies. All Bravais lattices and the most important two-atom lattices are analyzed. It is found that minimum energy is possessed by a triangular family generated by a primitive hexagonal lattice and yielding a triangular filamentary structure with two-dimensional periodicity. The elastic properties and phonon spectrum of the structure are determined and local stability of the corresponding metastable phase is proven. The properties of metallic hydrogen under pressure will be considered in a separate paper."
A recent NEB calculation based on DFT(see http://aip.scitation.org/doi/10.1063/1.3694793), however, showed that almost all of the currently predicted structures of metallic hydrogen are unstable at zero pressure, and there is no energy barrier between atomic phases and diatomic insulating phases of hydrogen. In addition, the conclusion of Brovman et al was based on simple approximations, and might require further scrutiny.