The High-Luminosity LHC aims to provide a total integrated luminosity of 3000 fb$^{-4}$ from proton-proton collisions at $\sqrt{s}$ = 14 TeV over the course of $\sim$ 10 years, reaching instantaneous luminosities of up to L = 7.5 × 1034cm$^{-2}$s$^{-1}$, corresponding to an average of 200 inelastic p-p collisions per bunch crossing ($\mu = 200$) . The upgraded ATLAS detector and trigger system must be able to cope well with increased occupancies and data rates. The performance of the upgrade has been estimated in full simulation studies, assuming expected HL-LHC conditions and a detector configuration intended to maximise physics performance and discovery potential at the HL-LHC, and is expected to be similar to current performance. Fast simulation studies have been carried out to evaluate the prospects of various benchmark physics analyses to be performed using the upgraded ATLAS detector with the full HL-LHC dataset.