I'd argue HCF were abandoned and though they can also still be dug out of the basement for convenience, a pointless mention in a messy Connections background conspiracy that needlessly convolutes everything doesn't amount to much in the way of being brought back. They're still as far as we know as dead as TRICELL.
If they knew what to do with Ada, they'd stop keeping her out with her goal unrevealed and wouldn't tiptoe around it so much. It would've been very easy to keep her in VILLAGE yet they scrapped her when she'd be a far more fitting addition to that particular plot than Spencer ever was. At this point the unsolved mystery isn't adding anything more to her character or the overall narrative, it's just dragging out, and I don't see how it would make sense for her to not have any intentions of working with Wesker further if she still wanted to keep an eye on him. Losing access to him by cutting ties completely would make that impossible.
It's not like with Simmons who she ultimately quickly took the chance to help kill when it presented itself, she'd probably have done it a lot sooner if she could've gotten close. She wanted Wesker to advance in power for her own benefit. She also must have known that he'd be able to get a sample even without her, Ada is no fool. The idea of her suddenly wanting no more to do with him despite having no way of knowing what would happen in Africa doesn't make sense to me.
Much like archives once claiming incorrectly that Alex was male and the convenience of Zeno existing, it all just strikes me as not having a clear idea of where to go next. Things can always change on a dime again. Ada fully intending to give Wesker the sample until questioning his intentions only for his pointless answer (despite "not paying her to ask questions") to suddenly stir her conscience is also a huge deviation from her doing it on orders from the rival company. RE:4 acts like the rival company doesn't even exist as they were the reason Wesker didn't go get the sample himself. Yet he shows he can purely for fanservice.
HCF obviously haven't been abandoned when they're mentioned in the latest game though. Being dead or unresolved doesn't mean abandoned, fans seem to have this wacky built-in notion of statutes of limitations and lack of object permanence just because things aren't addressed well or timely enough for them. The Family could be defunct by 9 too, but they're still mentioned in it, so haven't been "abandoned." You might not like certain choices or directions, just as I don't, but they are what they are.
Whether they know what to do with Ada or not doesn't matter, very little's ever pre-planned in general. That's normal for most ongoing stories. A lot goes into choosing what to cover in any given game. It's never a matter of not knowing what to do. They have many ideas but have to choose for any given project, with countless factors to influence that choice.
There's never an indication elevating Wesker was Ada's actual intent, only that he was a pawn and working with him served her "true purpose". She gave him G to survive and never gave him the dominant Plaga. Ada had no way of knowing Wesker would recover Krauser's body, whether in the original or remake. Those are the only two missions she's done for him we know of. There's never any reference to working with him afterwards, this seems to just be a misunderstanding. Ada cut ties with him because she betrayed him, with RE:4 adding the Simmons-like context of her viewing him as too much of a threat.
Ada was always going to betray Wesker either way, but she wanted to know his intentions, while previously the Umbrella revival subplot filled that role. Ada can betray Wesker both for HCF and her conscience, they aren't mutually exclusive. The remakes ignore almost anything not directly involved in their stories, because they generally try to "streamline" and are catered to a new, bigger audience allergic to complexity. Certain things don't receive the same build-up they once did, so implementing them would be awkward, while other things like Operation Javier are rewritten with entirely new context so nobody needs to have played DC. Just look how many new fans didn't even have a clue who Wesker was in RE:4. They constantly have to do balancing acts.
