  The advent of next generation radio telescope facilities, such as the Square
Kilometer Array (SKA), will usher in an era where a Pulsar Timing Array (PTA)
based search for gravitational waves (GWs) will be able to use hundreds of well
timed millisecond pulsars rather than the few dozens in existing PTAs. A
realistic assessment of the performance of such an extremely large PTA must
take into account the data analysis challenge posed by an exponential increase
in the parameter space volume due to the large number of so-called pulsar phase
parameters. We address this problem and present such an assessment for isolated
supermassive black hole binary (SMBHB) searches using a SKA era PTA containing
$10^3$ pulsars. We find that an all-sky search will be able to confidently
detect non-evolving sources with redshifted chirp mass of $10^{10}$ $M_\odot$
out to a redshift of about $28$ (corresponding to a rest-frame chirp mass of
$3.4\times 10^{8}$ $M_\odot$). We discuss the important implications that the
large distance reach of a SKA era PTA has on GW observations from optically
identified SMBHB candidates. If no SMBHB detections occur, a highly unlikely
scenario in the light of our results, the sky-averaged upper limit on strain
amplitude will be improved by about three orders of magnitude over existing
limits.
