This is not how EU law works. National courts are not at liberty to ignore the caselaw of the Court of Justice. If a national court (at any rate one against whose decision there is no appeal under national law) deliberately ignored a clear judgment of the Court of Justice, it would open its Member State to a potential suit in damages for breach by that court of its EU Law obligations by the persons whose rights have been denied as a result of the Court's failure to follow ECJ caselaw.

Nor, to be honest, is it how civil law systems work either, at any rate those I am familiar with (eg: France). If the highest court in the land with ultimate authority on interpretation decides in a clear statement of principle that a piece of legislation means X even if you are yourself very clear that the Court is wrong and that it is blindingly obvious that the words of legislation cannot by any stretch of the imagination possibly mean X, it would be extremely ill-advised (in fact, a clear case of professional negligence for a lawyer, I would have thought) to advise someone that "the legislation means non-X even though there are some decisions saying it means X."

In this particular case, given that we have not only a finding in Sturgeon that delays give rise to compensation but a very deliberate, clear confirmation of this in Nelson by the Grand Chamber (in which the Court was specifically asked by the applicants to reverse its Sturgeon decision), Reg 261/2004 must be regarded as a deliberate, clear and firm confirmation of the principle in Sturgeon, unlikely to be reversed any time soon.

Sure, there can always be theoretically a reversal of jurisprudence. This is true in common law jurisdictions as well as civil law jurisdictions. In the light of Nelson, though, it seems to me that this has as much chance of happening in the short term as the Pope converting to Islam. If compensation ceases to be available for delays in the forseeable future, it would have to come as the result of a change in the legislation (and there is no sign of that coming for now either, since the Commission has proposed to explicitly confirm the liability of airlines to compensation in cases of delays in its proposal for a revision of Reg 261/2004, albeit with higher delay thresholds).

All in all, therefore, it seems to me well beyond doubt that one can confidently and straightforwardly assert that, as things stand, an individual is in principle allowed to claim compensation for delays > 3 hrs under Reg 261/2004 (provided all the other conditions are fulfilled, of course) even though it cannot be entirely ruled out that, at some point in the future, the ECJ may reverse its jurisrpudence not can it be ruled out that the legislator may, at some point, decide to amend the legislation to exclude or limit such liability.