Signal is a centralized app, run by a company. If they are offered enough money or legal threat they will sell out or close.
I am sure people will make an argument that its FOSS and people will just fork it if it goes bad, but a new fork will have 0 users and Signal will still have all of your old contacts. Why not make a switch now? Before it is even more popular and you have more reasons to stay? Why fork it if there are already decentralized apps that use same encryption, like XMPP apps?
Sure you can find flaws in every app, including XMPP implementations, but if we will have to write code for a new Signal fork, why not just fix whatever is that bugs you in XMPP clients?
If you want to use Matrix, that is fine as well, we can always bridge the two open protocols. But you cant bridge Signal if their company doesn’t allow it.
We have that in XMPP and Matrix. The problem is then to talk to people on it they all have to join the server on which you host your build. What if that server goes down? If you pay for hosting you’re putting it into the hands of another corporation. If you self-host at home, what if your electricity goes out? Your internet gets cut off? Is everyone you convinced to ditch signal going to be happy and willing to sacrifice their convenience and ability to talk to people they want (or need) to talk to over ideology?
If we get hit by a big enough solar flare, everyone will be communicating by pigeon again. You make valid points. I haven’t actually used XMPP before and only just started with Matrix. I think OP is right that we should keep an eye on alternatives for when/if the time comes.