Logically, this chapter didn't change a thing since last week. The only thing it showed was a panel with Serena lying face-down on the ground, which was already the case last week. So the story made zero progress on this part of the plot.
As I said before Gildarts survived having his arm, leg and a few organs being removed by Acnologia and lived, so it's not that unbelievable to think he survived. Even more so when his character remains unfinished.
Dude, this whole thing about Serena = Yuri is solely based on that the two share a moderate resemblance to each other. If you take that away, it's based on nothing. Then Serena might as well be Erza's father or Jura's long lost brother. Are you telling me that Warrod, who was Yuri's best friend and had been for years, probably even decades, and who was thinking about him on his death bed can't recognize him, while we can despite we saw only a handful of panels of either characters? Are you telling me Makarov can't even recognize his own father, but we can? They might be old, but they aren't senile.
Also Warrod never had a particular back story and Precht is also so and so. The only one who truly had a real backstory, was Mavis.