This isn't quite true. There is one good reason to suppose the actor who played Beric will be back again as Beric: because he played Beric in the first instance. One can argue that the practicalities of the situation mean there is a good chance (even a likelihood) he won't be back. But this still does not change the fact that that he was unambiguously portrayed by that actor at least once already. That is direct evidence for the proposition that he will play him again, even if it turns out that he is unable to come back or they do not want him in the end. Or to put it another way: it is possible to have evidence supporting propositions that are untrue. This doesn't even rise to that level: it's evidence supporting a proposition whose truth value to us is currently unknown. What is known is any comprehensive wiki entry on Beric in the TV show will have to note that actor played Beric at least that one time: that is a fact that is not at all disputed. This is also goes some way to explaining why the quasi-Maege cannot really be confirmed properly in the wiki yet: because even if we may suspect she was intended to be Maege we do not have any direct confirmation she was. If they do put Maege in at some point later on played by a different actress, I should say our position would have to go to being that quasi-Maege was not Maege unless we have another very good and direct reason to suppose that she was. The only thing I can think of that would accomplish it in those circumstances would be someone known to be present directly acknowledging that Maege was present when Robb was first proclaimed King in the North...though even this might not be sufficient unless they also say Maege was the only woman present.