I haven't done MP survival, I'm in a coop adventure right now, but I think MP survival is where I want to be. As far as sharing/alliance, you could simply have a "share box" in your colony for other people to access, and connect with rail so it is easy to get to each other to see what is "in store." If you don't want to travel back to your colony, put whatever you want repaired into a "repair box" next to the machine and let the owner repair it for you while you wait (assuming you are going out adventuring together) -- only one person can use it at a time anyway. Those permanent iron boxes would be good for this. You may want to have several boxes near your rail station for passing visitors to check out... a "gift shop" LoL. If you want to gift valuable items, wait until you are there together to pass it to them.
Use your imagination. Cooperation is what you do, not a piece of computer code.
I think the most interesting environment would be where people are building and doing their own thing, so I am looking forward to seeing that type of server, and connecting to each other's colonies. I will finish the colony I am building on the coop server... I don't want to leave something half-done, but other people can take over and redecorate. Most of the friends I am making will likely follow. I don't see a lot of point in a server with only one colony... will someone be offended if someone else starts making changes, or changes the location altogether? It seems inevitable.
I am wondering... are there multiple starting points on an MP survival server? I hate to think that all of the PC colonies are clumped together by the colony quest. It is true that you can pick it up again and carry it anywhere once the quest is finished.
One thing though... do new NPCs show up on the map after the old ones are picked up by a colony? That would be bad for any new colonies if there are no colonists left. Here is something that is a real alliance activity... trading colonists so that you can share and train skills on a new set of people. Talk to a colonist, and at the same time the other person releases from their colony, so that you can invite them to join yours before they run away. This is a piece of coding that might need to be checked and updated... to have the new option appear when they are released while they are still talking to another player... or have the AI make the NPC stand still for 10-15 seconds before running away, so that a different player can invite them.
Also, can you team up to do dungeons in survival? I know that you can do this in Co-op... you just end up in the same instance together. If you enter a dungeon in Survival, is there only one instance until you leave the dungeon, or is a different instance created for everyone who tries to enter?
EDIT: to answer my own questions:
1) you can team up in survival from the console menu (~) Online: Information, click on a name and invite to join a team.
2) new NPCs do seem to show up on the map... probably after each server reset.
What I would like to see: ability to gift a colonist to another player (so they can use the skills to train their own colonists). Currently if you release a trained colonist in hopes of letting someone else use it, they seem to disappear much too quickly to be picked up by someone else. They do not seem to end up back at their start point, so where they end up is anyone's guess. I presume that they are deleted entirely and replace by new NPCs.
3) there does not seem to be a quest line for creating a colony (or working with the skill tree), like in other modes... you simply have to know what you are doing. There are a lot of new people who pick MP Survival to start, and so there is a lot of "helping with the basics" that needs to be done.
4) the Iron Box cannot be picked up once it is placed in MP Survival (and possibly not in MP Coop either). This is a bug. The box is a handy tool for sharing items with other players, but if you can't pick it up the world will become littered with left-over boxes. I don't care if it is destroyed when you pick it up (like the description says)... I just don't want to leave trash behind or have something interfere with another player's ability to build in that spot. FYI, you can enclose the Iron Box in blocks and still access it, so it can also be a secret stash in your colony, that can be used to share Raw Materials and share Tools as per the OP's request.