When you are secure enough with your band to be able to sit down and discuss how equipment and such should be distributed if a band member or all band members call it quits, you will find that your communication is strong enough to get you through anything. You will probably stay a long time.
It's the bands that don't like to communicate that have the real problems and the breakup plan is just one of those.
If your band has nothing, there really isn't much to having a breakup plan. However, I've got some buddies who's band purchased an $85,000 PA system. Now we are talking about some serious jack! This is the kind of thing that requires a clearly laid out plan on paper.
The problems get complicated with something like a PA system because you can't just split the PA system 5 ways....not easily anyway.
So the band needs to decide exactly how it will handle it if a band member decides to quit (most common) or how it will handle it if a band member is ever kicked out.
Have A Plan Before Buying New Gear
Let's say you plan on buying 3 SM58s for the band. Who is buying them? Is the band buying them? Is a single person buying them? Are 2 band members buying them? You can see right here that it would be a huge problem if 2 band members bought 3 microphones and one band member decided to leave. They'd be cutting the baby in half, like in that heart warming Bible story. So maybe, it would be smarter for everyone to buy their own microphones? Maybe not. Just put some thought into it.
Conclusion
I'm just as confident that your band will eventually break up as I am that it will eventually rain again. However, if everyone has their head on straight, it's possible to maximize the effectiveness of the band. When all band members are running on all cylinders, the band works. When two band members feel like no one will listen to their ideas, the whole system breaks down. You'll find these same people are no longer updating the band website either.
While sometimes, changing bands is a positive step, it is usually a step backward for a little while to get a new band to be gig ready. In most cases, if all musicians are talented in the first band, it's usually much smarter to stick with that band and work out your psychological issues.