In its press release linked below, The City UK Points out potential impact of Brexit on financial stability and personal finances of millions of people. According to the release, 36 million policyholders across the UK and EEA could be affected.
The report underlines the potentially harsh consequences of a hard Brexit and the need for continuity and certainty in the field of financial contracts. With regard to (re)insurance in particular, I think one will often need to distinguish between regulatory and contractual ramifications of a hard Brexit. While insurers from the UK would be treated as third country carries in the EU (and vice versa) if passporting rights expire, under contract law, rights and obligations may remain enforceable, especially for "old contracts".
That being said, given the continuing uncertainty, March 2019 approaching quickly and upcoming renewals, insurers and reinsurers as well as policyholders are well advised to consider their options and take respective safeguards now.
Thirty-six million insurance policyholders across the UK and EEA, and £26 trillion of outstanding uncleared derivatives contracts could be impacted if the UK and EU fail to agree on a solution.