Hypothetically, for whatever reason, aviaries just don't come to pass. We don't end up getting any type of new animal enclosures beyond the existing exhibits and habitats. What then, in your eyes, would be a sufficient (or close-to-sufficient) replacement?
As much as I want aviaries, I think I'd be mostly okay with an animal pack of 7 different habitat birds. Something like, gray crowned crane, helmeted guinea fowl, emu, saddle-billed stork, black swan, golden pheasant, kiwi. Or name your species, I know some people really like the secretary bird or ground hornbill or whatever, and that's totally fine. No matter how you look at it, there's a drastic shortage of birds in this game, even just considering the mostly-flightless ones that would work well enough in open air habitats. I think that a substantial addition to the bird roster would help mask the fact that we wouldn't have aviaries... as it stands, 1 new bird roughly every other DLC release isn't ideal for this outcome.
Or, alternatively, would anyone be okay with throwing realism to the wind here and just getting your eagles and parrots and toucans and whatever else and have them function more or less like any other animal? I think that would be a massive letdown, much more so than being skipped over altogether.
Slightly off topic, but I discovered earlier that one of the semifinalists for the competition that resulted in Magnet the polar bear's inclusion in the original Zoo Tycoon was a bald eagle. It's kind of crazy to think we could've ended up with a bald eagle all the way back then in the first major zoo sim, but people voted on an actual clone instead. For the record, two of the other semifinalists were a fossa and a pair of koalas, which also would've resulted in new species being added. Just thought that was really interesting, with regard to the flying bird discussions that keep cropping up surrounding this game.
I think at this point, after such a long time and so much effort placed by frontier in such a feature, it would be fair to give them as much additional time as they need. No company works on something for well over a year to simply just compromise on a lesser alternative at the end. This is usually the case unless that compromise is a must as the original idea is just not viable. The issue with that alternative reality is that in this case, the work would have been stopped a while back and birds would have simply being added to the game with an alternative plan.
For the sake of this thread I will discuss what an acceptable compromise would be for me, (not that it has any bearing on what will end up happening in real life) Birds are as everyone probably know by now, even if they had never visited a real life zoo before this game, a central and very basic element of zoos. When you first enter the game map, what do you hear? Birds, yet you do not see any, besides a compromise in game performance what that should tell you is how important it is to have birds in a zoo. This along, hundreds of other reasons that I will not list in this thread should make a case for birds being added in any manner possible.
Ideally we would be able to have walkthrough aviaries, habitat birds, etc etc, but if this was no longer possible, then an acceptable compromise for me would be the birds added alongside enrichment items, that include a variation of looping animations. An example would be a Toucan on a standing tree trunk with branches, that will hop alongside the branches, an African grey parrot that will walk on rope and hang upside down every now and then, an Indian hornbill resting on a banyan tree trunk that will spread its wings and fly to the very top of it. Of course that there will be need to be a variety of animations, not just a single one, still, far easier than having the birds as habitat animals.
Having the birds tied to enrichment items when adopting them would open up the possibility of designing their habitats as the player sees fit. If you are building a temperate zoo in North America or Europe you can create glass winter enclosures inside a birdhouse building and even summer outdoor ones if you like. You can also recreate the majestic walkthrough aviaries of the warmer U.S regions and lush Southeast Asian Zoos. The possibilities here would be endless, as the barriers alongside the animations would be tied to an enrichment radius that the player would be able to control to suit his/her needs.
The one thing that would be totally unacceptable to me when it comes to birds, particularly since we have waited this long, is having them go the route of the reptiles/amphibians, where they come in a standard one size fits all mesh/glass box and call it a day. This would not only cripple creativity beyond believe but it would remove all sense of realism from the game, as the player's zoos would look even less and less like their real life counterparts.
PS: I did not mention in the original post, that we would of course need all the aviary mesh sections required to create elaborate aviaries with the above reference option. Thought it was too obvious, but still, worth mentioning it. The current construction glass panels would have to be adjusted as well since they have very poor visibility, we either get construction glass panel that are comparable to the current ones in the barrier system or a flex color option for them, so players can adjust them to their specific needs.