What do we do if SETI is successful?

Get better camouflage so we don't get get found in the Dark Forrest. https://en.wikipedia.org/wiki/Dark_forest_hypothesis

>The name of the hypothesis derives from Liu Cixin's 2008 novel The Dark Forest, as in a "dark forest" filled with "armed hunter(s) stalking through the trees like ghosts". According to the dark forest hypothesis, since the intentions of any newly contacted civilization can never be known with certainty, then if one is encountered, it is best to make a preemptive strike, in order to avoid the potential extinction of one's own species. The novel provides a detailed investigation of Liu's concerns about alien contact.

Following that:

> The Berserker hypothesis, also known as the deadly probes scenario, is the idea that humans have not yet detected intelligent alien life in the universe because it has been systematically destroyed by a series of lethal Von Neumann probes.