  The use of continuum emission radio galaxies as cosmological tracers of the
large-scale structure will soon move into a new phase. Upcoming surveys from
the Australian Square Kilometre Array Pathfinder (ASKAP), MeerKAT, and the
Square Kilometre Array project (SKA) will survey the entire available sky down
to an ~100uJy flux limit, increasing the number of detected extra-galactic
radio sources by several orders of magnitude. External data and machine
learning algorithms will also enable some low resolution radial selection
(photometric redshift binning) of the sample, increasing the cosmological
utility of the sample observed. In this paper, we discuss the flux limit
required to detect enough galaxies to decrease the shot noise term in the error
to be 10% of the total. We show how future surveys of this type will be limited
by available technology. The confusion generated by the intrinsic sizes of
galaxies may have the consequence that surveys of this type eventually reach a
hard flux limit of ~100nJy, as is predicted by the current modelling of AGN
sizes by simulations such as the Tiered Radio Extragalactic Continuum
Simulation (T-RECS). Finally, when considering the multi-tracer approach, where
galaxies are split by type to measure some bias ratio, we find that there are
not enough AGN present to achieve a reasonable level of shot noise for this
kind of measurement.
