I think maybe Separate Ways will elaborate some more on how the post credits scene fits into the greater scheme of the game. I'm sure they deliberately kept quite a few plot points in the dark (such as U-III, who, in this version of RE4, is the second Verdugo who mysteriously vanishes at some point) in order to use them in Separate Ways, and the whole "what's going on with Wesker" is most likely one of them.
That being said, I think the post credits scene can be interpreted in two main ways regarding RE5 - one, it really does sets up a remake for RE5. Two, it simply ties into the original RE5 and Capcom has no intention of remaking that one (for now, anyway). I think it works on both fronts. Deliberately so, most likely. Capcom probably doesn't know either yet just where they want to go with this. lol
This is pretty much the same conclusion I came to and like Jonipoon, I would rather they start a new "trilogy" of games with remakes of both Resident Evil 1 and Code Veronica before they jump straight into 5.
I think there's potential in treating these games as a trilogy of sorts, that way they can scale it back with Resident Evil 1 and gradually increase the scope with Code Veronica and 5, all while focusing on one linear story revolving around Albert Wesker. But at the same time, given how similar RE5 already is to RE4, it does kinda make sense for them to jump straight into 5 while the iron is hot and I certainly wouldn't complain with whatever order they do end up going about these remakes after how incredible RE4 turned out to be.
One interesting thing to note however, is that the director of Revelations 2 who co-directed both Resident Evil 2 and 4 remake with one of his game designers from Rev 2, also co-directed Resident Evil 5. So it does beg the question of whether or not he's even interested in making RE5 again, who's influence can already be felt in the RE4 remake, or if there's any kind of bias in choosing to remake 5 before any of the others.
But one thing is for sure, and that's that Yasuhiro Anpo and Kazunori Kadoi definitely deserve their flowers given the strides they've made to return the series to its former glory in both big and small ways, starting with RE5 which opted for a more serious tone than its predecessor and attempted to wrap up the on-going narrative that RE4 abandoned.
Then we have Revelations 2, which I've always described as a love letter to the fandom for its inclusion of long absent favorites like Claire Redfield and Barry Burton, in his first mainline starring role. Even the reveal of Alex Wesker who was teased in RE5 and failed to be mentioned anywhere in RE6 made the game feel like a proper sequel to RE5 despite being a spin-off. And all the general lore connections and references to past games made the series feel interconnected again. It was everything that had been missing from the series at that point and even though it wouldn't be the return to form the Revelations series claimed to be, it was a hell of a leap in the right direction.
Enter Resident Evil 2. The game that single handedly restored faith in the brand for Resident Evil fans who didn't quite like the latest rebooted direction RE7 was steering the franchise in. Everything we disliked about it, be it the first person gameplay, the tone, atmosphere, or lack of main series protagonists and their portrayals, was all addressed in this remake that set a new bar for the series and this same care and detail is just as present in the RE4 remake as it was in RE2, whether you're a fan of the type of game it is or not.
Whatever they do next, I'm all in as long as we keep getting this consistent stream of quality that this team has been delivering. It honestly boggles my mind that they're not the ones in charge of the entire series, because if there's one thing they've proven, it's that they get Resident Evil. Meanwhile, the main series has no idea what it even wants to be from game to game.
Personally, I’d rather see them remake RE1 first in order to setup the confrontation between Chris and Wesker in a RE5 remake, but that raises the additional question of whether their encounter in Code Veronica should be skipped over.
I've once suggested that if they ever did remake Code Veronica, that I would like to see Chris' confrontation with Wesker be playable and be made into some huge cinematic experience like the fight with Liquid Ocelot at the end of Metal Gear Solid 4 since it would have likely been the last time we get to experience their rivalry. But with a 5 remake potentially on the table, we have at least 2 more opportunities to see their rivalry unfold again.
With that said, the Wesker fights in Resident Evil 5 were absolute highlights of that game, and I can't imagine how they'd improve or top those encounters in a remake. Not saying they couldn't, but maybe they don't have to either? I mean, if it ain't broke... But I don't think that's enough reason to skip over their confrontation in Code Veronica either. I think it's important to Chris' development to get his ass kicked by Wesker and then come back beefier as a result of how helpless he felt during their first battle. And after the RE4 remake, I can see this encounter being more Krauser knife fight than full on boss fight like we got in RE5.
As for Resident Evil 3's post-credit scene, I saw a post on Twitter that is probably the likely case as opposed to Capcom hinting at some new story they're going to tell with Jill (which would have been awesome), that suggests it's merely Jill at Chris' apartment in Europe, hence the green shirt and punching bag, as this is apparently written somewhere in the lore. At the very least, hopefully this means she'll play some kind of role in Code Veronica if they ever do plan on revisiting it, otherwise, why even include the scene at all?