I think when we see S-IV’s from the Reclaimer cast back, most/all of them will be wearing GEN3 iterations of their original armors. I think that’s the better way to go for a sense of visual continuity and that it lends credence to the GEN3 platform being a universal evolution and the cutting edge of MJOLNIR.
That said, if 343 hasn’t totally abandoned the idea of armor cores going forwards, a GEN2 core should absolutely come to Infinite at some point. It’s a very distinct and historically significant aesthetic from Halo’s past, love it or hate it. In the lore, it’s indisputably a more ubiquitous and significant platform than Mk V [B], so with all the love that core is getting, it makes sense that a GEN2 core can and should come into the picture at some point.
And since Infinite has already got several cores that arguably clash with each other visually, tossing a GEN2 core into the mix shouldn’t cause any issues. There will be classic Halo purists who whine about it, of course, but if they don’t have an issue with the myriad “sore thumb” cosmetics in Infinite (Fractures Cores, goofy attachments like Cat Ears and Playing Cards, armor/kill effects, et. al), then they absolutely shouldn’t have a problem with a GEN2 core.
The biggest question is whether 343 has decided to abandon the core system or not. They’ve left way too much ambiguity around their plans for how they’re going to address cosmetics in Infinite going forward. Are core locks going away? If so, to what extent? Are cores themselves going away? If so, in Season 3, or 5, or 8, or when?
I understand entirely that breaking their silence on all of this right now, given that we’re months away from significant new content actually coming to the game, might not make a ton of sense to them. But given the confusion around these details and Jerry Hook’s comments around them during the S2 launch Community Stream, I think it would be appropriate for 343 to clarify in at least broad strokes what their plans are for all of this. After all, they are expecting people to spend money every week on cosmetics for this game. The least they can do is inspire some confidence that this system will get better rather than worse over time.
Anyways, tangential rant aside, and assuming that cores aren’t going away entirely as a customization feature for Infinite, a GEN2 core should be a priority. It’s probably not realistic to expect that all the H4-5 armors will be featured for it, especially not at first, but they should absolutely target the “Greatest Hits” from those games.