  UHECRs have attracted a lot of attention due to their challengingly high
energies and their potential value to constrain physical processes and
astrophysical parameters in the most energetic sources of the universe. Current
detectors have failed to detect significant anisotropies which had been
expected to allow source identification. Some indications about the UHECR
composition, which may become heavier at the highest energies, has even put
into question the possibility that such a goal could be achieved soon.
  We investigate the potential value of a new-generation detector, with 10
times larger exposure, to overcome the current situation and make significant
progress in the detection of anisotropies and thus in the study of UHECRs. We
take as an example the expected performances of the JEM-EUSO, assuming a
uniform full-sky coverage with a total exposure of 300,000 km2 sr yr.
  We simulate realistic UHECR sky maps for a wide range of possible
astrophysical scenarios allowed by the current constraints, taking into account
the energy losses and photo-dissociation of the UHECRs, as well as their
deflections by magnetic fields. These sky maps, built for the expected
statistics of JEM-EUSO as well as for the current Auger statistics, as a
reference, are analyzed from the point of view of their intrinsic anisotropies,
using the two-point correlation function. A statistical study of the resulting
anisotropies is performed for each astrophysical scenario, varying the UHECR
source composition and spectrum as well as the source density.
  We find that significant anisotropies are expected to be detected by a
next-generation UHECR detector, for essentially all the astrophysical scenarios
studied, and give precise, quantitative meaning to this statement. Our results
show that a gain of one order of magnitude in exposure would make a significant
difference compared to the existing detectors.
