Combining the Signal protocol with the NOSTR protocol is a very intuitive thing to do, and it almost doesn't require any major modifications to either protocol.
Discussion
Would be cool to rip up a NIP with nostr:nprofile1qqspwwwexlwgcrrnwz4zwkze8rq3ncjug8mvgsd96dxx6wzs8ccndmcpzemhxue69uhk2er9dchxummnw3ezumrpdejz7qtxwaehxw309anxjmr5v4ezumn0wd68ytnhd9hx2tmwwp6kyvt6w46kz6nyxa6nxumc8pu82wfj09shvwt2wau8qu3cxvukxuesdd3nxufkws6nvanyx46njufsxvehsmtgwd4nvcejw43n7cnjdaskgcmpwd6r6arjw4jszxrhwden5te0dehhxarj9enx6apwwa5h5tnzd9az77vr4lw and make it cross compatible. That would be insane.