  The high precision and large kinematic coverage of the data from the HERA-I
running period (1994-2000) have already allowed precise extractions of proton
parton distribution functions. The HERA-II running program is now underway and
is expected to provide a substantial increase in the luminosity collected at
HERA. In this paper, a study is presented which investigates the potential
impact of future HERA data on the proton PDF uncertainties, within the
currently planned running scenario. Next-to-leading order QCD predictions for
inclusive jet cross sections at the LHC centre-of-mass energy are presented
using the estimated PDFs. Finally, the effect of a possible future measurement
of the longitudinal structure function, F_L, on the gluon distribution is
investigated.
