It sounds like a dichotomy going on all the way around; it sounds like you and the other couple kinda do and kinda are afraid to...like the first time a kid jumps off of a high dive; they really want to feel the thrill, are scared of the thrill, want to climb back down, are ashamed of facing their friends mockery if they do etc. until they just do it.
The only difference being this is four people instead of one.
There are games that help couples delve into swinging in levels of intensity and touch; the first level being very light flirtatious types of things. I think you can find them here on this site.
You might research it a little, talk to your wife about whether or not she thinks this might work, and maybe she could talk about it with the other couple's wife. Everyone would go into this with the understanding that anyone could have veto power at any time. Believe it or not, that fact, when established, actually gives more freedom to enjoy and push into things.
Also make sure everyone grasps the levels of soft swing versus full swap. Establishing that you'd like to gingerly and tentatively experiment with soft swing only often can give the group more freedom to push further, because everyone knows that you can always pull back if someone gets too uncomfortable.
And, if someone really does get too uncomfortable, do pull back, and explain that while this was an experiment, the friendship is far too valuable to lose on something like this.
When you do this, by the way, whatever level you end up with, whether it's the softest of soft swing (like just having sex with your own partner in the same room as the other couple having sex) or full swap, any level is okay.
We've done it at all levels over time and have enjoyed all of them. It's got to be the right couple for the right level.
And, by the way, in my opinion it should not be a factor whether or not they are moving away. Here I present yet another contradiction, do it like there would be no tomorrow, and do it like you'd be swinging and playing with them the rest of your lives.
And, finally, in my opinion, it's really important for the girls to stay v. tight with each other and the guys to stay v.tight with each other. This, I believe, will become obvious.
And everyone will tell you, talk, talk, talk. Tell how you feel--at every stage and a week later. Talk to your spouse and talk to the other couple; nothing hidden makes fo r excellent relationships.