In an ideal world, maybe/hopefully. But Signal is already awful at hiding your identity¹, tying a public key to your already leaky Signal account isn't going to improve anything.
Theoretically, yes, but practically? Countries like Germany already legally require you to provide your ID to buy cryptocoins at non shady businesses.
So in reality for most people crypto remains perfectly tracable for all time to their identities. But then again, no one uses crypto as a peer to peer currency anyways...
