I think most of those buildings will be unlocked using Traditions rather than ethics in Banks. I remember seeing at least one of the buildings as an option there.
Yes, I hope that will be the case. I have seen the paradise dome in the Harmony Tradition and other buildings would fit well with other Traditions. (e.g. the stock exchange in Prosperity)
We have been told that Psionic Theory will only be researchable for Spiritualists now, so they aren't getting rid of that design entirely it seems.
If I'm not mistaken psionics will become an ascencion perk. You might still need spiritualist to pick that perk though.
Presumably it won't be that easy to switch back and forth between ethics though. You have to wait 20 years after embracing a faction to embrace another, and you can only do it if the ethic holds at least 20% attraction, which might take some work. A divided population means it'll be harder to gain tradiions, and embracing a faction will likely hurt your influence gain and happiness for a while, plus it takes 250 influence per switch and might deactivate some of your civics until you swtich back. And you could get really unlucky and not have the techs show up for a long time. Hopefully it'll be a viable strategy but not an obvious one.
Of course you're not going to do it for every single tech / building.
But some are definitly worth it. Like ministry of benevolence + frontier commisars. After you have those it gets easier to pull your pops to your new ethos anyways, and it will stabilise your empire in the long term.
I'd say the stock exchange and the research institute are also worth it. And from going Individualist for a bit you can pick up the entertainment forum along the way.
Also you don't even have to change your ethics very often. Once is actually enough. Start the game with ethics that allow you to unlock the buildings you want, and then switch to your favorite ethics after you have them.
For example: Your goal is an individualist & materialist, synth based empire. But at the start you actually pick collectivist + pacifist + materialist. Wait until you get paradise dome, frontier commisars and the ministry of benevolence, and then switch to individualist ethics.
If you run with individualist policies from the start of the game you should have enough individualist attraction to make this happen (and your slaves will have even more individualist attraction!).