The American Astronomical Society has produced this (lightly edited) statement on Twitter:
A report by experts representing the global astronomical community concludes that constellations of bright satellites in “low Earth orbit will change ground-based optical & IR #astronomy & could impact the NightSky for stargazers.”
One is the SATCON1 report itself. The other contains the SATCON1 Working Group Technical Reports.
TL:DR satellite mega-constellations have an impact ranging from negligible to catastrophic but some mitigation is possible in some areas. Some of the mitigation may be expensive in terms of:
compute power — generation of ephemerides; recognition and masking of trails in images ; correction of induced artifacts
imaging technology — mid-exposure shuttering to avoid recording of satellite passage is not possible in many cameras; multi-slit spectroscopy needs to know which objects may be contaminated and which may not
development time — for example, the development of per-pixel mid-exposure shuttering may be possible with CMOS detectors but it is likely to be years before they become available at adequate performance
legal requirement: creation and enforcement of constraints on satellite operators
satellite operator costs — darkening , attitude control and fitting of sunshades to satellites; adherence to legal constraints.