I thought it was a neat sequence, but it made no sense at all.
All you see about young child Eveline (outside of the Ship videotape) are hallucinations (as explained in the files... Ethan must have gotten infected at some point during the early game) and all the "phantoms" you see at the end in the Guest House are Eveline messing with your mind. It is obvious that Eveline still has "mental" powers over infected (both Molded - that's why she often seems to pop up as Granny in areas where you are about to be swarmed or just were swarmed by Molded or jumped by Jack) and is using that to hurt you, appearing as "psychic shock waves" to you as a form of hallucination.
Also the scariest part in the game is a big giveaway in that sense: In the detention room sequence it would make no sense if Eveline herself wasn't attacking you if she was some kind of ghost or apparition, she has to use Molded to carry out the attack. She only seems to be able to directly harm you if she is in your vicinity and you are infected enough so she can make some of your synapses in your brain go crazy or fry themselves, otherwise she has to rely on her minions and puppets.
Loved all the "ghost Eveline" sequences though, straight up Alma from FEAR (fitting considering one of the authors of the story was working on both games).
Going to write a longer summary of my thoughts tomorrow now that I have beaten the game, actually mad some screencaps of the end credits "newspaper" (it is actually an Umbrella file) that actually has additional lore information especially why Eveline was aging.
Also want to throw in that the old Racoon City Umbrella was dismantled in 2004, considering that ALL the events in RE7 take place between (I think) 2014-2017 it seems obvious that the new Umbrella is not a "good" organisation but literally Umbrella 2.0 with a focus on selling barely controllable BOWs to the highest bidder. Mia and her partner were working for them and supposed to incognito export them from one Neo-Neo-Umbrella (kek, just gonna call it BlueBrella from now on) facility to one in Central America, shit ecalates and BlueBrella makes the best of it by just using the chance to gather more data by observing Evi and the Bakers via Helicopter (see the "are they watching us?" photo in both the mines and the teaser demo) and by setting up a surveillance lab in the mines and using Lucas as an insider for close observation after they healed him at least enough to stay himself (still a sociopathic psycho though). Seems like Eveline got to the lab observers eventually though.
Considering how self-love/hating, uncaring, shitty and remorseless Chris has been in RE6 and after additionally having to deal with the shock of having lost Piers I'm not suprised that his old crush on Wesker caught up with him and made him join up with BlueBrella for a nice paycheck. I really hope what it is, "he is still good actually and just infiltrating them! or "They are actually good guys who just call themselves Umbrella" would be eye-roll inducingly bad and boring writing. Fine with Hunk too though.