The FLASH2020+ upgrade project [41; 42] is aiming at covering this empty space by combining an upgrade of the accelerator, an ambitious R&D program for the seed laser [43] and a new undulator setup. With such an upgrade new scientific avenues are opened in various fields: in general, the higher repetition rate ideally caters to photon-hungry experiments that need to average over many (thousands) shots to accumulate statistically meaningful data. Very often though, such experiments provide an unprecedented information depth making them very interesting for scientists. Examples of such experiments are often found in the field of spectroscopy. For example, photoelectron spectroscopy at FELs is often limited in the ability to accept intense photon pulses due to space-charge effects in the emitted electron cloud. This fundamentally limits the achievable signal levels even with the most advanced spectrometers that accept emission cones of \(2\pi\) solid angle [44]. Only a high repetition rate machine can then enable complex experiments at a reasonable time. Other experimental techniques that strongly benefit from high repetition rates are spectroscopies where emitted photons are spectrally analyzed (such as resonant inelastic X-ray scattering or X-ray emission spectroscopy) [45; 46; 47; 48; 49] with notoriously weak signal yields, especially at soft X-ray and XUV wavelengths even at high photon numbers. These techniques though provide a tremendous amount of information through their element and chemical state selectivity as well as their polarization and orientation sensitivity due to the involved stringent dipole selection rules. Of course, the high repetition rate is also very beneficial when extremely dilute samples or rare events are being studied [50; 51; 52; 53]. Here, only the gathering of a sufficient amount of data in reasonable measurement durations allows gaining a satisfactory signal above background. Furthermore, a large number of pulses in a short time interval allows for sampling huge, multi-dimensional parameter spaces not only concerning shot-to-shot FEL beam parameters, but also extending to pump-probe laser parameters (e.g., relative delay to the FEL pulse, pulse lengths, wavelengths, intensity, polarization) and other sample parameters (temperature, external fields, positions, orientations,...). Especially the field of spectroscopy benefits from the increased longitudinal coherence, i.e., the smaller energetic bandwidth of the pulses, where pulse parameters can come close to the optimal point in the trade-off between energy and temporal resolution at the Fourier limit. Here, FLASH will be operated in a regime with sufficient temporal resolution to visualize electronic processes while still providing sufficient spectral resolution to selectively study specific chemical elemental resonances as well as the respective chemical shifts. Fully coherent pulses are also a prerequisite for transferring modern coherent (spectroscopy) techniques from the laser world to the X-ray realm. Here, first steps have been achieved, but it is becoming apparent that higher-order optical constants are even weaker at shorter wavelengths than in the optical regime. Nevertheless, such techniques often provide information that is unavailable to more traditional methods, such as the spatial motion of excitations in transient grating methods [54; 55]. Some of those experiments can be performed in a quasi-background-free manner, but full harvesting of results from such novel X-ray methods requires fully coherent beams at high repetition rate in order to bring weak signal levels above noise floors. With the FLASH2020+ upgrades, the facility will be ideally positioned to open up such complex experiments to the scientific community. In this work, the parameters of the new facility and the expected performance for the new seeded FEL are reported together with a description of the current capabilities at FLASH.