MNblockhead
A Title Much Cooler Than Anything on the Old Site
Or perhaps reconsider how you structure your games. You can organize your games to be more flexible with party makeup without throwing story and plot lines out the window. My regular group consists of adults in their mid-30s to early 50s. We have jobs, spouses, and children. I have other friends who can't commit to regular participation in an ongoing campaign, but would like to get together now and then, when they are able.
So, first, I try to structure my campaigns and sessions to allow people to miss a game, or to drop in occasionally, without anyone feeling like they are messing up the adventure or campaign.
Second, at the end of a session, we pull out our calendars and agree on the next date.
The result is that scheduling is simple, quick, and there is no stress about people missing out or bad feelings over people not "committing" to the campaign.
How this looks has changed from campaign to campaign. My first campaign after returning to TTRPGs with 5e was completely homebrew, including the plot lines, and most of the adventures. Sessions were 8 hours, long enough to finish an adventure or at least to get to point where the group was not in the middle of something that would make it difficult if a player couldn't make the next session or if a player that wasn't in this session wanted to join in on the next session. The conceit of this campaign was that months or years passed between most sessions. A new threat/opportunity brings the group back together. Or their was a long period of travel between session and the group meets up at the new locations in their quest for whatever McGuffin I set up. It was a good balance between creating an ongoing shared story and an episodic string of "one shots" that could easily accommodate both missing and drop-in players.
That campaign was similar to how we played in the 80s where we would just buy one of the thin softcover modules and run our characters through it for a session or two, with different groups of players from one session to the next. The only difference is that I was creating my own adventures and keeping to one setting and tying the sessions to overall plot lines.
Curse of Strahd was a bit more challenging, but the sandbox nature of it and the fact that there were a good number of side quests and encounters that could nicely fill a single 6-8 hour gaming session made it doable. The only time my organization style didn't work well was in Castle Ravenloft, where we did end sessions in the middle of exploring the castle. That was the only time in years where I had to struggle to make sure I was able to schedule the same group for the next session.
My current campaign is Rappan Athuk, a massive mega dungeon that takes years to play through. This style of play works very well for how we schedule games. Generally the game ends with the party completing some self-set objective and ending back at their base (they've restored and secured a nearby ruined castle). PCs of missing players are assumed to be running things in the castle and the town that's sprung up around it when they are not delving with the rest of the group. Bringing in guest-player PCs is easy without having to suspend disbelief or hand-wave. Also, every player has at least one backup PC back at the castle, so their players can get back in the game quickly if their PC dies or it unavailable for some other reason.
