Nah with OIAL I feel like it makes sense for the final scene to be
the Lauren and Judie threesome since they're the ones who've been with MC throughout the entire thing, while everyone else felt like a side girl who could pretty much be removed from the story and it'll still turn out fine.
With Eternum it's going to be a bit difficult to stick to the threesome limit in OIAL because none of the main girls feel like they're stuck to their cliques or being left out of the main plot this time around (in fact the relationship development of the girls as a group is light years ahead of OIAL, with 0.5 building that further if the early preview screenies are any indication), so there's a greater chance that a final orgy with all of them could happen (provided that you're following the harem route).
So yeah, while it's possible that I could end up wrong, I'm still optimistic given what we've seen so far and what's being teased for the future.