UPDATE: April 11, 2019
Leaders of the European Union have granted the UK a six-month extension before Brexit takes place.
The new deadline - 31 October 2019 - averts, for now, the prospect of the UK leaving the EU without a deal. European Council President Donald Tusk said his "message to British friends" was "please do not waste time".
Theresa May, who had wanted a shorter delay, said the UK would still aim to leave the EU as soon as possible. The EU has ruled out any renegotiation of the withdrawal agreement.
UPDATE: January 16, 2019
If the UK leaves the EU without a deal, British passport holders will be considered third country nationals by countries within the Schengen area after 29 March 2019.
This means that, technically, UK nationals will be, with regards to nationality, eligible for a blue card in order to take up employment in any of the 25 blue card-issuing EU countries.
More info: UK Government
Working in the European Union
As a Network specialized in connecting EU employers with qualified candidates, we receive many questions from UK nationals as to whether the EU Blue Card is available in order to work in the European Union.
The answer: currently, it is not an option. Perhaps in the future.
When the brexit negotiations-result does not include an agreement on the free movement of people, and no other such arrangement has been agreed upon, then logically, the Blue Card would be available to UK nationals; as it basically is available to all non-EU nationals.
EU Blue Card
The EU Blue Card is a work- and resident permit for skilled/educated non-EU nationals. In order to be eligible for the Blue Card, one must have a employment contract -or binding employment offer- issued by an organization located in a blue card-issuing country.
25 EU countries issue the Blue Card. The UK, Ireland and Denmark have never issued the Blue Card.
Any news regarding brexit and the Blue Card will be published here.