@MarkScottRobson A good question.
From the technical side:
1. The #Fediverse network (not #Mastodon network; Mastodon is one of many Fediverse software) is based on a @w3c standard called the #ActivityPub protocol.
Think for example the protocol behind emails, SMTP. Or the protocol behind surfing the web which is HTTP/S.
Because it is a #WebStandard, there is always a software available.
Here are some examples of software for the Fediverse network:
a. #Firefish (f. #Calckey) - flagship instance is https://firefish.social
b. #Rebased - see https://c.wtf
c. #BookWyrm - see https://bookwyrm.social - think #GoodReads
d. #Pixelfed - flagship is at https://pixelfed.social - think #Instagram
e. #Lemmy - see https://r.nf - think #Reddit and #Stackexchange (or #Quora for that matter)
f. #WriteFreely - flagship https://write.as - think #blogging platform
g. #PeerTube - see https://p.lu - think #YouTube or #Vimeo
h. #Friendica - think #Facebook
i. #Hubzilla and #Streams - think full blown CMS + Community with #SocialWeb functionalities built into its core (instead of using add-ons)
j. #Chirp - https://chirp.social - think #Groups with #moderation features and some customisation.
And those are just a few. See this for more at https://en.wikipedia.org/wiki/Fediverse && here https://codeberg.org/fediverse/delightful-fediverse-apps
Now, the above examples are just the software options for running a community or service (which you can do if you know how).
Each have a different purpose. Each have a different UI and UX.
Then there are also #Frontend software. These are software that will give you a different layout for the software the server is using.
For example, you don't like the default Mastodon UI? Then log in your Mastodon account here: https://fe.soapbox.pub and use a UI that is similar, if not the same, as #Twitter / #twitter
How about mobile? There are also a lot to choose from with different features, design, and experience. You can check out a list here: https://codeberg.org/fediverse/delightful-fediverse-clients
2. Lifespan.
Let's say the Mastodon team call it quits, for whatever reason. Will the network die? No.
Again, Mastodon is just one of many fediverse software. You can just move to a new server or instance of your choice.
Secondly, the Mastodon source code is #FLOSS / #FOSS (or #OpenSource). In fact, there are already a lot of forks of Mastodon, adding other features that are not found in the mainline Mastodon code.
And the servers/instances running Mastodon? They won't die just because the Mastodon team called it quits. They'll just find a Mastodon fork and move to it. Or, start their own.
3. If you're adventurous, you can run your own solo or family instance/server. Or maybe a public server that is invite-only.
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That's just 3, there are many more.
#BlueSky? Yes, they do offer federation (a.k.a. interoperability) but the protocol they are using is not a WebStandard, they started their own and so far have no plans to support the webstandard ActivityPub protocol.
In fact, right now, federation with BlueSky is turned-off. They are not yet concentrating on it.
However, once they do, I personally would not be surprised if the generous Fediverse server/instance hosts start to setup their own federated BlueSky server/instance, which in turn will definitely help grow the BlueSky network.
And who knows? Maybe BlueSky will implement the ActivityPub protocol and join the Fediverse network? If this happens, then it becomes a matter of choice. Which UI and UX and features do you like?
But, until that happens, in my opinion, staying in the Fediverse is your best bet.