1/ A couple of points about the issue of UK nationals and EU citizenship post-Brexit. First, the court case referred to here. The full text of the ruling is not available. The quote simply notes that the CJEU has not ruled on the issue yet. It does not decide the issue either way
2/ This specific case (Walker) concerns a legal challenge to the EU law waiving short term visas for UK visitors to the EU post-Brexit. The EU General Court ruled that the legal challenge was inadmissible as individuals can't directly challenge EU legislation in the EU courts.
3/ EU General Court ruling of 23 Oct 2019 here: curia.europa.eu/juris/document…
Friday's ruling is from the CJEU on appeal. Not known what it said yet. This is a request for interim measures but the main case will have the same standing issues.
Friday's ruling is from the CJEU on appeal. Not known what it said yet. This is a request for interim measures but the main case will have the same standing issues.
4/ However there are other ways to raise the issue that are more likely to have standing, and which are less convoluted than challenging the visa waiver. cf this planned litigation about UK citizens' political rights post-Brexit:
5/ Unfortunately I have seen this fake law quote doing the rounds. I am sparing the person who tweeted it from a pile on. It's from a newspaper article by a non lawyer. The "and this means therefore..." part does not appear in any EU court judgment to date. 
6/ I expect there may be more direct challenges before EU courts on this issue (all facing possible standing problems), and also more cases before national courts. National courts can then ask the EU courts to rule on the EU law issues. As it stands, it's an open question.
7/ Having said that, I'd be surprised if EU courts ultimately say that UK citizens retain EU citizenship. No one should act on the assumption that they will do so. UK nationals in EU should take the necessary steps to secure their status as the withdrawal agreement is implemented
8/ CJEU case law says that withdrawing nationality of a Member State can be reviewed for lack of proportionality, as it results in loss of EU citizenship. 3 issues here: a) are UK nationals still EU citizens? b) UK courts think EU case law unconvincing ->
9/ ...and c) loss of nationality in a terrorism-related case would likely be considered proportionate anyway, as the CJEU is deferential to Member States here.
I've discussed the 'loss of Member State nationality/EU citizenship' issues further here: eulawanalysis.blogspot.com/2019/03/citize…
I've discussed the 'loss of Member State nationality/EU citizenship' issues further here: eulawanalysis.blogspot.com/2019/03/citize…
10/ Uncertainty.
