Constructs such as “It has come to this” are often used in rhetorical or other statements to emphasise that there has been a sequence of events ending in some present circumstance. For example, “How has it come to this?” does not really demand an answer, but points to the present circumstances (usually to the their bad aspects).
“If it has come to this ...” suggests that despite a train of events that led to the present, we must just accept the present and act somehow for the future.
“Years of violence and a bitterly fought election have ruined the nation. If it has come to this ...”