  The prospects for future blazar surveys by next-generation very high energy
(VHE) gamma-ray telescopes, such as Advanced Gamma-ray Imaging System (AGIS)
and Cherenkov Telescope Array (CTA), are investigated using the latest model of
blazar luminosity function and its evolution which is in good agreement with
the flux and redshift distribution of observed blazars as well as the
extragalactic gamma-ray background. We extend and improve the template of
spectral energy distributions (SEDs) based on the blazar SED sequence paradigm,
to make it reliable also in the VHE bands (above 100 GeV) by comparing with the
existing VHE blazar data. Assuming the planned CTA sensitivities, a blind
survey using a total survey time of ~100 hrs could detect ~3 VHE blazars, with
larger expected numbers for wider/shallower surveys. We also discuss
following-up of Fermi blazars. Detectability of VHE blazars in the plane of
Fermi flux and redshift is presented, which would be useful for future survey
planning. Prospects and strategies are discussed to constrain the extragalactic
background light (EBL) by using the absorption feature of brightest blazar
spectra, as well as cut-offs in the redshift distribution. We will be able to
get useful constraints on EBL by VHE blazars at different redshifts ranging
0.3-1 TeV corresponding to z=0.10-0.36.
