I think any personal AI agent at this point is "very sticky", not just Muse. You really aren't going to switch when a lot of the value is in the agent memory and there's no easy way to export that, similarly to how you aren't going to switch away from Spotify when it's learned all your song preferences which you can't export. Right now, maybe the agent memory is small enough that if you ask the agent to export you'll get most of it out (Claude has notably made official export instructions to encourage switching from ChatGPT in the past), but in the future the memory will be too large and complex to do that effectively, and platforms could also block the memory export or degrade it deliberately.

So, in the long run you pretty much have to pick one personal agent and stick with it, and switching is costly (unless you are using an open agent that lets you just download the memory, in which case it actually becomes cheap, because AI agents make other parts of switching way easier in general). For the purposes of Meta this means whatever user they get they'll probably keep.

HOWEVER, the thing that Muse doesn't have is network effects. They're running into the exact same problem as ChatGPT in this area, IMO. There's no reason for you to be running specifically Muse even if all of your friends are running it. So that gives other vendors a chance to catch up.