Yeaaah, the new Copernicus Data Space Ecosystem is online (since 23 January?) and open for registration: https://dataspace.copernicus.eu
Registration seems to work smoothly and download of Sentinel-2 L2A as early as of 2016 only takes a few seconds (i.e. no cold archive)... the roadmap also is full of goodies like STAC, processing API, full Sentinel archive, still this year!