  Recent successful lasing of the Linac Coherent Light Source (LCLS) in the
hard x-ray regime and the experimental demonstration of a possibility to
produce low-charge bunches with ultra-small normalized emittance have lead to
the discussions on optimistic scenarios of operation of the European XFEL. In
this paper we consider new options that make use of low-emittance beams, a
relatively high beam energy, tunable-gap undulators, and a multi-bunch
capability of this facility. We study the possibility of operation of a
spontaneous radiator (combining two of them, U1 and U2, in one beamline) in the
SASE mode in the designed photon energy range 20-90 keV and show that it
becomes possible with ultra-low emittance electron beams similar to those
generated in LCLS. As an additional attractive option we consider the
generation of powerful soft x-ray and VUV radiation by the same electron bunch
for pump-probe experiments, making use of recently invented compact afterburner
scheme. We also propose a betatron switcher as a simple, cheap, and robust
solution for multi-color operation of SASE1 and SASE2 undulators, allowing to
generate 2 to 5 x-ray beams of different independent colors from each of these
undulators for simultaneous multi-user operation. We describe a scheme for
pump-probe experiments, based on a production of two different colors by two
closely spaced electron bunches (produced in photoinjector) with the help of a
very fast betatron switcher. Finally, we discuss how without significant
modifications of the layout the European XFEL can become a unique facility that
continuously covers with powerful, coherent radiation a part of the
electromagnetic spectrum from far infrared to gamma-rays.
