Software Heritage is a non profit initiative whose ambitious goal is to collect, preserve and share the source code of all software ever written, with its full development history, building a universal source code software knowledge base. Software Heritage addresses a variety of needs: preserving our scientific and technological knowledge, enabling better software development and reuse for society and industry, fostering better science, and building an essential infrastructure for large scale, reproducible software studies. We have already collected over 4 billions unique source files from over 80 millions repositories, and organised them into a giant Merkle graph, with full deduplication across all repositories. This allows us to cope with the growth of collaborative software development, and provides a unique vantage point for observing its evolution. In this talk, we will highlight the new challenges and opportunities that Software Heritage brings up.