@qfr you really shouldn't be trying to protect other people. If your group doesn't hit those milestones you should all still go through with it. The fact your team is that at-risk should be exposed rather than covered up.
Yes, it would suck for those who stay, but that is what needs to happen so that leadership can see the dumpster fire they're riding thinking everything is fine. Let the wheels come off so meaningful change can happen.
My group is similar. I fill a vital role on my team, covering a shift nobody else is willing to work (they can't even get contractors to take it), and do more of our bread and butter work than almost all my peers save for the one who is more senior than me. I won't waste one second thinking about staying despite how it would sc--w over the people I work with.
Management needs to see it can fall apart in order to respect that it can happen. Plus, if the anecdotes here are at all true they might call you back and you can negotiate for more money.