JH clarified in another quote that it was because of tears of joy, because they liked the episode and it was a time the whole cast (since EK and KC came back and EBR is leaving) actually got to be together for a scene possibly for the last time.
ETA: found the quote "We were crying the entire shoot. Not just because it’s sad, but because we know that the end is coming up and this is our last full-season finale…. It was just kind of surreal. It’s a really incredible script — everybody really put their all into it — and there is so much action. It’s very exciting, and really emotional.” So not that necessarily it was joy joy, but more of crying because of the experience more than saying the finale is sad.
I don't think so. EK left. An appearance in the finale (which is one of the things Beth was referring to) is one thing, coming back is a whole other ordeal. I would sooner believe that they would have Alena """"replace"""" Felicity than Curtis.
It could be a concern, but I don't think her quotes indicated it either way. She would say all of this stuff if Felicity didn't get killed off anyway. Heck, in 523, literally none of the main characters died ("cliffhanger" notwithstanding, they never were going to kill any of the leads and most of the fans knew it), and they still used descriptions very much like the ones Beth used.