The main reason why East Vs West is getting pushed aside is that it's using the much older clausewitz engine. HOI4 will blow East Vs West (at least graphically) completely out of the water and will likely have a lot of features the early engine couldn't handle.
Paradox also seems hesitant to release games with a smaller scope since they tended to do much more poorly compared to the other titles, see March of the Eagles and Sengoku.
If I was on the EvW team at this point I would be considering how much we could rip and port to the new engine. Likely a lot would have to be redone but it would seem better than being reduced to the bargain bin by Paradox and basically getting no support.
Err, I haven't heard anything about a new engine for Hearts of Iron 4; I know EU4 uses Clausewitz, and I'm pretty sure HOI4 will as well. For that matter, even their newest RPG is going to use Clausewitz (heavens know how, though). To be fair, though, if the game had come out on anything resembling "on schedule", it wouldn't have looked completely obsolete, and being based off an obsolete engine (that is to say, not Clausewitz) didn't hurt Darkest Hour any. I agree on Sengoku and March of the Eagles, but those were always intended to be budget-bin interims to sit as preludes to Crusader Kings 2 and Europa Universalis 4, respectively. To a degree, though, even Crusader Kings 1 sat in that little category due to the Snowball (or whatever the Russian company was) fiasco.
If I were the EvW team or the Paradox Interactive team in charge of greenlighting or denying gold status, I'd focus on finishing the features that they said they were going to do and can still do, and trim off what they can't do instead of clinging to hope and pushing for the everything. It's all and well for self-published games to have a gradual release schedule since they can look forward to years, if not decades of development based on incremental funding sources over that duration, but when all is said and done, they are working for a corp which can't keep shoveling money down a black hole in the hopes of an eventual pay-off. Hence why I'm so amused by this announcement; it suggests that a game publishing company is actually trying to put it out using the former system instead of being the latter. I suspect they're just trying to cut their losses and avoid the PR disaster that was the Magna Mundi cancellation, to be honest, but while I'm a little suspicious of it, it's still better than a straight cancellation.