I believe there may be a small chance that they will find the remains of microbial life 50–65 km above the surface of Venus, not because I believe there is a possibility of indigenous life in the upper atmosphere of Venus. You see, there is scientific evidence establishing that diatoms and other microorganisms are wafted up into Earth’s upper stratosphere and beyond 25–100 km above Earth’s surface. [Alexa R. Van Eaton, Margaret A. Harper, and Colin J. N. Wilson, “High-Flying Diatoms: Widespread Dispersal of Microorganisms in an Explosive Volcanic Eruption,” Geology
41, no. 11 (November 2013): 1187–90, doi:10.1130/G24829.1
; Milton Wainwright et al., “Isolation of a Diatom Frustule Fragment from the Lower Stratosphere (22–27 Km)-Evidence for a Cosmic Origin,” Journal of Cosmology
2013, volume 22 (August 9, 2013): 10183–10188. ]
From there, passing dust particles will transport a few of these microorganisms to the upper atmosphere of Venus. Another transport route would be large meteoroids bombarding Earth with sufficient force to export Earth rocks and soil into interplanetary space. For example, astronomers have calculated that meteoroids have deposited about 20,000 kg of Earth material on average on every 100 square km of the Moon’s surface.
So, it is inevitable that the remains of Earth life have been transported to Venus’s upper atmosphere by natural means.
Earth was hostile enough 3.83 billion years ago to, against incredible odds, to have life emerge. Elsewhere, we can just starting with habitable zones: water, UV, planetary electric field, planet rotation rate/tidal locking, planet rotation axis tilt, astrosphere stellar magnetic wind, then the galactic habitable zones inc. co-rotation zone (just inside of), far from super novae, staying near plane of rotation, far from any large galaxy, and much more. The math is insanely against it.
So, sorry, just color me as a skeptic.