I don't see cameras in your example.
Do you want to invest 4K for what? A 4K projector will not deliver a 4x sharper picture then a HD projector..
Streaming on 4K is useless at the moment. Because almost nobody can look at 4K content yet...
Expect to pay 6 / 7 times as much money to go full 4K now then HD. ( i know i have about the same setup in an OBV trailer)
But i have gone for Decklink cards instead of a Ultrastudio..
You have about 10K worth of BMD hardware in your screenshot.. Not to mention all new SDI cabling you need to pull for 4K. Not to mention 12G sdi cabling can only reach 40 meters with the right cable and UHD connectors.
Your projector wont have a 12G-sdi connection so you need a Teranex mini SDI to HDMI in there.
Same applies for your Lobby tv's.. And if they are not 4K you need to downscale that image from the Teranex mini.
Same applies for your content computer. HDMI to SDI teranex mini.. Or get a MAC were you can put in a Decklink card and some playout software than can handle a Decklink card.
Remember that EVERY! source connected to the Atem needs to be the same resolution and framerate.. So you can't mix HD and 4K sources together.
Not sure what you will gain for your church in 4K instead of HD. Unless you have a lot of money to burn / spend in a project..