  Cold dark matter subhalos are expected to populate galaxies in numbers. If
dark matter self-annihilates, these objects turn into prime targets for
indirect searches, in particular with gamma-ray telescopes. Incidentally, the
Fermi-LAT catalog already contains many unidentified sources that might be
associated with subhalos. In this paper, we determine the probability for
subhalos to be identified as gamma-ray pointlike sources from their predicted
distribution properties. We use a semi-analytical model for the Galactic
subhalo population, which, in contrast to cosmological simulations, can be made
fully consistent with current kinematic constraints in the Milky Way and has no
resolution limit. The model incorporates tidal stripping effects from a
realistic distribution of baryons in the Milky Way. The same baryonic
distribution contributes a diffuse gamma-ray foreground which adds up to that,
often neglected in subhalo searches, generated by the smooth dark matter and
the unresolved subhalos. This configuration implies a correlation between
pointlike subhalo signals and diffuse background. Based on this semi-analytical
modeling, we generate mock gamma-ray data assuming an idealized telescope
resembling Fermi-LAT and perform a likelihood analysis to estimate the current
and future sensitivity to subhalos in the relevant parameter space. We find a
number of detectable subhalos of order ${\cal O}(<1)$ for optimistic model
parameters and a WIMP mass of 100~GeV, maximized for a cored host halo. This
barely provides support to the current interpretation of several Fermi
unidentified sources as subhalos. We also find it more likely to detect the
smooth Galactic halo itself before subhalos, should dark matter in the GeV-TeV
mass range self-annihilate through $s$-wave processes.

High Energy Astrophysical Phenomena;Cosmology and Nongalactic Astrophysics;Astrophysics of Galaxies;High Energy Physics - Phenomenology