The field of cosmology is entering an era of large collaborative surveys. With it, breakthrough discoveries are expected to come from measurements of the Comic Microwave Background (CMB) polarization field and a detailed mapping of the large scale structure. Three main scientific targets in cosmology have been identified; primordial gravitational waves, the number of relativistic species and the mass of the neutrino. In this talk I will discuss why the mass of neutrino, while a realistic target in cosmology, is no longer considered a guaranteed discovery. Measuring the neutrino mass requires an exquisite lensing measurement combined with a precise determination of the amplitude of primordial fluctuations. Recent work has shown that the latter is currently our limiting factor. I will then continue by providing two possible solutions to this problem. At the same time, we should think how to further advance lensing beyond the CMB. For that purpose I show theoretical work on lensing estimates using intensity maps, such as redshifted 21-cm field, a very promising future probe in cosmology.