I voted mirrors because of many reasons.
Most of these "new things" have a solution that can be made already, some with drawbacks, some without. Depends on who you are.
Telescopes are the only thing I couldn't think of a solution for, and neither could I really think of a reason to have them other than vanity, which is fine. If you're doing it for vanity, just get a custom block model. Easy.
Birds: If you don't like bats, get a resource pack to replace bats with birds. The birds may act odd but hey, you got birds. There's also a 1 command block thing for birds too.
Villager mansion: Just get rid of all the baddies in the evil villager mansion and dump some dudes in there. Easy fix.
Camera:
f2
Mirrors do have a solution.
And that is re-building literally everything from one room into another, getting another person with your exact skin to copy your every movement flawlessly, ect ect ect. I think that mirrors have the hardest solution, which is why I'd like mirrors to be implemented. But that's just me.
