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!

Copernicus Data Space Ecosystem | Europe's eyes on Earth
Welcome to the Copernicus Data Space Ecosystem, an open ecosystem that provides free instant access to a wide range of data and services from the Copernicus Sentinel missions and more on our planet’s land, oceans and atmosphere.The Copernicus Data Space Ecosystem not only ensures the continuity of the open and free access to Copernicus data but also extends the portfolio for data processing and data access possibilities. Delve into the data immediately via the Copernicus Browser or register to create an account and have an even better comprehensive exploration experience.