The deep biosphere (subsurface life, including below the seafloor in rocks and sediments) makes up a substantial portion of the planet and harbors vast amounts of microbial life. The Center for Dark Energy Biosphere Investigations (C-DEBI) specializes in the exploration of microbial life, geochemistry, and hydrology in the subsurface (NSF-funded Science Technology Center). Since C-DEBI was established (2010), the number of scientists with a primary focus on deep biosphere research has increased within the last decade as a direct result of efforts from C-DEBI. The objective of this white paper is to present the broad ideas of what the future of deep biosphere research may look like, from the perspective of early career researchers (graduate students, postdoctoral scholars, pre-tenure faculty).